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Page 1: Abstracts IAUS286


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IAU Symposium 286

Comparative Magnetic Minima:

Characterizing Quiet Times in the Sun and Stars

3 – 7 October 2011, Mendoza - Argentina

Page 3: Abstracts IAUS286


IAUInternational Astronomical Union

IAFEInstituto de Astronomıa y Fısica del Espacio

UTN – FRMUniversidad Tecnologica Nacional Facultad Regional Mendoza

CONICETConsejo Nacional de Investigaciones Cientıficas y Tecnicas

AFOSR SOARDAir Force Office of Scientific Research – Southern Office of AerospaceResearch and Development

SCOSTEPScientific Committee on Solar-Terrestrial Physics

COSPARCommittee on Space Research

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CONAEComision Nacional de Actividades Espaciales

CLAFCentro Latinoamericano de Fısica

ANPCyTAgencia Nacional de Promocion Cientıfica y Tecnologica

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Conference Committees

Scientific Organizing Committee

Hebe Cremades (Chair) Johanna Haigh

Sarah Gibson (Chair) Kanya Kusano

Thomas Ayres Cristina Mandrini

Alisson Dal Lago Georgeta Maris

Daniel Gomez Valentn Martınez Pillet

Manuel Gudel Andrey Tlatov

Gustavo Guerrero Ilya Usoskin

Margit Haberreiter Adriana Valio

Jeffrey Hall

Local Organizing Committee

Cristina Mandrini (Chair) Sergio Dasso

Laura Balmaceda Marcelo Lopez Fuentes

Hebe Cremades Marıa Luisa Luoni

German Cristiani

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Page 7: Abstracts IAUS286

Session 1

Solar and Stellar Minima


Hebe CremadesSarah Gibson

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Nature and the Significance of Solar Minima

E. Priest

University of St Andrews, Scotland, UK

Abstract. A review is given of the solar cycle, including its cause in a deep-seated dynamo,and its many effects. These include the nature and structure of the photosphere, the upper solaratmosphere, the solar wind and the influence on the Earth’s space environment and climate.The unusual nature of the last solar minimum has awakened an interest in solar minima notjust as gaps between maxima, but has of intrinsic interest in their own right.

E-mail: [email protected]

1 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Solar and Stellar Activity Diagnostics and Indices

M. Thompson


Abstract. How does one go about charting the ups and downs of a stellar activity cycle? On theSun, the question has been answered in a variety of ways over the centuries, starting with simplesunspot counts extending back to the time of Galileo (although the sunspot cycle itself was notrecognized until the 19th century), extending to very recently recognized signatures such ashelioseismic mode shifts, subtle total irradiance changes, dramatic X-ray variations, the ”rush tothe poles” in the coronal green line, migration of torsional oscillations; and phenomena possiblyrelated to Maunder-like behavior such as the contemporary steady decay in the average fieldstrengths of sunspots, and a parallel decline in the average umbral/photospheric temperaturecontrast. For the stars, on the other hand, the available cycle charting tools not only aremuch fewer, but also the sheer number of potential targets makes for a somewhat dauntingobservational challenge. The best known stellar effort was that started by Olin Wilson at Mt.Wilson observatory (no relation) fifty years ago, based on a clever differential measurementof the Ca II H and K chromospheric emissions, which vary by 25%, or so, over the typicalcycle of a Sun-like star. Wilson’s HK program targeted about 150 nearby bright dwarf stars,and he identified solar-like decadal cycles in many of the sample members, particularly thoseof low solar-like activity; but also erratic variables among the more active objects, as wellas ”flat-liners,” generally found in the lowest activity tier. The latter ”non-cycling” objectsperhaps are analogous to the Maunder-minimum Sun. The Wilson program has been carriedon to contemporary times in several guises, and extended to measure rotation periods andeven differential rotation signatures in the HK time series. Aside from the HK index, thereare relatively few other good measures of cycling behavior. The coronal X-ray luminositypotentially is a powerful signature of cycles, but only a small handful of objects have beenstudied in this way so far, mainly because the existing heavily-oversubscribed high-energyobservatories are ill-suited for time-domain projects. The same is true for ultraviolet emissions,which like X-rays vary much more strongly over a cycle than HK, but also like X-rays arechallenging to schedule for long-duration efforts (although some progress was made by the IUEsatellite, thanks to its 17 year mission). Very recently, however, the stellar prospects havebrightened with the advent of the Kepler mission. The precision photometry delivered bythe transit-hunting telescope can track the changing numbers of starspots on even relativelyinactive stars, thereby mimicking the traditional sunspot counts through which the solar cyclewas originally identified. The latitude migration of the starspots (”butterfly pattern”) canbe deduced by changes in the apparent repetition periods owing to differential rotation. Itmight also be possible to follow subtle long-term luminosity changes with Kepler if the highprecision of the photometry can be translated to a high accuracy measurement as well. Finally,asteroseismology with high-cadence Kepler data could be used to identify the mode shifts thatare known to accompany the rise and fall of the solar cycle.

E-mail: [email protected]

2 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

How Well Do We Know Sunspot Number?

L. Svalgaard

Stanford University, USA

Abstract. We show that only two adjustments are necessary to harmonize the Group SunspotNumber with the Zurich Sunspot Number. The latter being inflated from the 1940s to thepresent by 20% due to weighting of sunspot counts according to size of the spots. The GroupSunspot Number before 1885 is too low by ∼50%. With these adjustments a single sunspotnumber series results. Of note is that there is no longer a distinct Modern Grand Maximum.

E-mail: [email protected]

3 3-7 October 2011 – Mendoza, Argentina

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Session 2

Dynamos and Cycle Variability


Daniel GomezGustavo Guerrero

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Dynamo Action and Magnetic Activity in the Sun and Stars

A. S. Brun and the STARS2 team

CEA-Saclay, France

Abstract. Many stars exhibit magnetic activity with the Sun being the archetype of cyclicactive stars. Recent progress in multi-D numerical simulations and observations have now madeit possible to draw a more coherent picture on what sets up such magnetic activity. Stellarparameters such as age, mass and rotation rate contribute certainly to explain why some starshave cyclic activity while others do not as they modify the conditions under which the stellarglobal dynamo operates. Still some difficulties remain as some stars with almost identical stellarparameters seem to exhibit different level of activity or magnetic properties. In this talk we willreview the recent progress made by our team to decipher the mystery behind stellar activity.

E-mail: [email protected]

5 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Cycles and Cycle Modulation in Large-Scale Turbulent Dynamos

A. Brandenburg


Abstract. Our understanding of solar and stellar dynamos is unfortunately still quite limited.Numerical simulations of convection in spherical shells do produce large-scale magnetic fields,and they are also cyclic, but the magnetic field tends to show poleward migration, contrary towhat is seen in the Sun. Although this behavior disagrees with what is seen in the Sun, meanfield dynamos also tend to produce poleward migrating magnetic fields. A deeper understandingof the agreement between mean-field models and direct numerical simulations is profitable,because it teaches us details about the theory. Such comparisons with simulations have alreadytaught us that dynamo action is caused by alpha effect and turbulent diffusion, both of whichare tensorial integral kernels in space and time. Furthermore, cycle modulation is caused byfluctuations of the dynamo coefficients in space and time. Characterizing such fluctuationshas therefore become an integral part of mean-field dynamo theory. The test-field method hasbecome a primary tool for analyzing simulations in this way.

E-mail: [email protected]

6 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Solar and Stellar Dynamos: Origins of Variability of Cycle Minima

R. Arlt

Astrophysikalisches Institut Potsdam, Germany

Abstract. It is very likely that the key to understanding the generation of the large-scalemagnetic field of the Sun lies in the imperfection of the solar cycle. The diversity of activityminima observed over the last centuries needs to be reproduced in global dynamo models.This review will focus on the possibilities to obtain variability from mean-field dynamos, thetwo essential ways being the introduction of stochasticity or the introduction of nonlinearities.Another ingredient to the variability of solar and stellar cycles are global, magnetic instabilities.This talk will address the possible interaction between fully periodic dynamo modes and globalinstabilities which add another time-scale to the system. Current-driven instabilities require aminimum magnetic field strength and can thus act as a limiting mechanism for the growth ofthe field, and they can in turn provide a contribution or modulation of the alpha-effect, whichis most likely the main generator of large-scale magnetic fields.

E-mail: [email protected]

7 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Magnetic Helicity Fluxes and their Effect on the Solar Dynamo

S. Candelaresi, A. Brandenburg


Abstract. Motivated by coronal mass ejections we consider magnetic helicity fluxes in mean-field and direct numerical simulations. In forced turbulence the shedding of magnetic helicitycan alleviate catastrophic alpha-quenching and allow for strong mean magnetic fields at highmagnetic Reynolds numbers. Even magnetic helicity fluxes withing the domain are shownto alleviate the quenching. The restriction of magnetic energy decay due to the presence ofmagnetic helicity is investigated in the context of its topological interpretation. It is shown thatduring reconnection magnetic helicity does not change significantly, but changes from linkingto twisting.

E-mail: [email protected]

8 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Kinematic Dynamo Models of the Solar Cycle: Past, Present andFuture

D. Nandi

Indian Institute of Science Education and Research - Kolkata, India

Abstract. The magnetic activity of stars such as the Sun originates in their interior throughcomplex interactions between plasma flows and magnetic field. A useful tool of modeling thisactivity is the kinematic approach, in which, plasma flows are used as prescribed inputs tosolve for the magnetic field. In this talk, I will review the historical development of kinematicdynamo models of the solar cycle, highlight current trends and comment on future prospects.

E-mail: [email protected]

9 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Global MHD Simulations of Stellar Dynamos and the Ingredients forLarge-Scale Field Organization

M. Browning1, B. Brown2, M. Miesch3, A. S. Brun4, J. Toomre5

1University of Exeter, UK2U. Wisconsin, USA3HAO/NCAR, USA4CEA-Saclay, France5U. Colorado, USA

Abstract. Magnetism exerts a pervasive influence on solar/stellar evolution, but a full under-standing of the means by which magnetic fields can become organized, either in space or intime, has remained elusive. Convection, rotation, shear, and other effects all appear to playroles. I will review what we have learned about each of these ingredients in the dynamo process,using 3-D MHD simulations of dynamo action in global spherical shells of convection. I willfocus in particular on some recent results regarding the strength and morphology of fields, thepresence or absence of magnetic cycles, and the role of solar/stellar tachoclines. I will also drawsome comparisons between our results and the predictions of mean-field dynamo theory.

E-mail: [email protected]

10 3-7 October 2011 – Mendoza, Argentina

Page 18: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Dynamo Action and Magnetic Buoyancy in Convection Simulationsin Simulated Tachoclines

G. Guerrero1, P. Kapyla2

1NORDITA, Sweden2Helsinki University, Finland

Abstract. One of the existing hypothesis on sunspot formation is the buoyant emergence ofmagnetic flux tubes created by the strong vertical shear at the tachocline. In this scenario, themagnetic field has to exceed a threshold value before it becomes buoyant and rises through theconvection zone up to the surface. Several physical constrains are required to be fulfilled forthis model to be feasible. In this seminar I will present the results of numerical simulationsof thermal convection including a narrow radial shear layer. The model tries to mimic, withinthe numerical limitations, the conditions in the solar convection zone and the tachocline. Theexcitation of dynamo action as well as the buoyant properties of the generated magnetic field areexplored under different conditions. The implications of the results on the sunspot formationprocess and the solar dynamo are also discussed.

E-mail: [email protected]

11 3-7 October 2011 – Mendoza, Argentina

Page 19: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Tayler Instability and Stellar Magnetic Fields

F. del Sordo, A. Brandenburg


Abstract. The stability properties of magnetic fields in fluids have been subject to debate fordecades, being an important ingredient in the analysis of stellar magnetic fields. We presentresults of 3D global, numerical simulations aimed to study the stability and the evolution ofthe Tayler instability in presence of axial field and differential rotation. We show the evolutionof current helicity generated by the development of the instability and compare numericalsimulations with analytical calculation of the growth rate. The test-field method is used toquantify the occurence of an alpha-effect. Then we discuss this study in the context of stellardynamos.

E-mail: [email protected]

12 3-7 October 2011 – Mendoza, Argentina

Page 20: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Understanding the Origin of the Extended Minimum of Sunspot Cy-cle 23

A. Munoz Jaramillo1,2, D. Nandi3, P. C. H. Martens2,1

1 Harvard-Smithsonian Center for Astrophysics, USA2 Montana State University, USA3 Indian Institute of Science Education and Research - Kolkata, India

Abstract. The minimum of solar cycle 23 was characterized by very weak polar field strengthand a large number of sunspot-less days that was unprecedented in the space age. This has hadsignificant consequences in the heliospheric space environment in terms of record-high cosmic-ray flux and low levels of solar irradiance - which is the primary natural driver of the climatesystem. During this un-anticipated phase, there was some speculation as to whether the solarminimum could lead to a Maunder-like grand minimum which coincided with the Little IceAge. Here we present the first consistent explanation of the defining characteristics of thisunusual minimum based on variations in the solar meridional plasma flows, and discuss howour results compare with observations. This work is funded by NASA Living With a Star GrantNNX08AW53G to Montana State University/Harvard-Smithsonian Center for Astrophysics andthe Government of India’s Ramanujan Fellowship.

E-mail: [email protected]

13 3-7 October 2011 – Mendoza, Argentina

Page 21: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Helioseismic Probing of Dynamo Related Flows

F. Hill


Abstract. Large-scale internal bulk flow fields are essential components of solar-cycle dynamo models.The most important flows are the meridional (north-south) flow, which is thought to set the amplitudeof the solar cycle in flux-transport dynamos, and the zonal (east-west) flow or torsional oscillation thatappears to be tightly correlated with the timing of the cycle. Helioseismology now provides us withthe ability to track these flows as functions of time, depth and heliographic location. Using 16 yearsof data from GONG, SOHO, and SDO, we can track the flows over all of cycle 23, and the start of thepeculiar cycle 24. These observations have revealed that the cycle 23–24 minimum was extended bythe same length of time that the zonal flow took to migrate to the latitude at which activity appears,and that the zonal flow associated with cycle 25 has yet to appear. This talk will review the currentstate of these observations and discuss their implications for dynamo models and the Sun.

E-mail: [email protected]

14 3-7 October 2011 – Mendoza, Argentina

Page 22: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Analyzing the Evolution of the Photospheric Magnetic Field in Termsof Spherical Harmonics and Consequences for the Solar Dynamo

M. L. DeRosa1, A. S. Brun2, J. T. Hoeksema3

1 LMSAL, USA2 CEA-Saclay, France3 Stanford University, USA

Abstract. Time series of synoptic maps from the Wilcox Solar Observatory [from 1976 to the presentday] and from the Michelson Doppler Imager [from 1995 to the present day] are analyzed in terms oftheir spherical harmonic decomposition. We illustrate how the rise and decline of the flux emergencerates throughout a sunspot cycle are reflected in the evolution of the various harmonic mode coeffi-cients. We further discuss the interplay between the primary [dipole-like] and secondary [quadrupole-like] dynamo families of harmonic modes, and their role in the reversal of the axial dipole during solarmaximum. Such magnetic effects are measurable for many other stars, and observations of large-scalesolar magnetic fields enables us to make connections with stellar dynamos.

E-mail: [email protected]

15 3-7 October 2011 – Mendoza, Argentina

Page 23: Abstracts IAUS286

Session 3

Comparative Solar Minima from Sun to Earth


Margit Haberreiter

Andrey Tlatov

David Webb

Page 24: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Helioseismology: A View of the Solar Interior

Y. Elsworth

University of Birmingham, UK

Abstract. This meeting is aimed at understanding activity minima in the Sun and stars. Most ofthe tools that we have for studying the Sun and stars are exterior measures. However, observationsof the natural, global oscillations of stars provide a key measure of the internal conditions. For theSun, this is the topic of helioseismology. I will provide an introduction to the topic and will focus onhow magnetic activity influences the properties of the oscillations and hence what we can infer fromchanges in the frequencies, amplitudes and widths of the modes.

E-mail: [email protected]

17 3-7 October 2011 – Mendoza, Argentina

Page 25: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

What is the Sun’s High-Latitude Rotation Doing?

M. Thompson1, R. Howe2 , R. Komm3, F. Hill3, T. P. Larson4 , J. Schou4, M. Rempel1

1HAO/NCAR, USA2University of Birmingham, UK3NSO, USA4Stanford University, USA

Abstract. Helioseismology and surface Doppler observations of the Sun’s rotation have revealed ahigh-latitude branch of the torsional oscillation. The onset of this high-latitude speed-up has beenreported to be absent coming out of the recent solar minimum, leading to suggestions that Cycle 25may be delayed or may even not happen at all. We present how the high-latitude rotation has behavedfrom 1996 up to the present time, and suggest an interpretation for the observed behavior.

E-mail: [email protected]

18 3-7 October 2011 – Mendoza, Argentina

Page 26: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Reconstruction of Magnetic Field Surges to the Poles from SunspotImpulses

N. V. Zolotova, D. I. Ponyavin

St. Petersburg State University, Russia

Abstract. The time-latitude diagram of the photospheric magnetic field of the Sun during 1975-2011(Kitt Peak NSO, SOLIS NSO, SOHO MDI data) is analyzed using: (i) Gnevyshev idea on pulsedstructure of sunspot cycle; (ii) Gauss random field approximation of sunspot clustering; (iii) a fluxtransport model. It is demonstrated that poleward migrations of magnetic trailing polarity are closelyassociated with the impulses of sunspot activity. By means of their fitting the sunspot clusters andpoleward surges are reconstructed up to the 10th cycle. Results of modeling are compared with theproxy data on polar field reversals in the past.

E-mail: [email protected]

19 3-7 October 2011 – Mendoza, Argentina

Page 27: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Total Solar Irradiance, Absolute Value and an Estimate of a Long-Term Trend from Minimum to Minimum

W. Schmutz, A. Fehlmann, W. Finsterle, M. Sutter

PMOD/WRC, Switzerland

Abstract. PREMOS is an experiment on the French satellite PICARD consisting of absolute radiome-ters and filter radiometers, which were built by PMOD/WRC (Thuillier G., Dewitte S., Schmutz W.,2006, Adv. Space Res. 38, 1792-1806). PREMOS measures Total Solar Irradiance and spectral so-lar irradiance in selected wavelength bands. PICARD was launched on June 15, and first light ofPREMOS was on July 27, 2010. PREMOS is operational since September 6, 2010. The PMO6-Ainstrument of PREMOS is the first radiometer in space, which has a SI-traceable irradiance calibra-tion in vacuum. The calibration has an uncertainty that is smaller than the difference between thediscrepant absolute TSI values from VIRGO/SOHO and TIM/SORCE. Thus, the PREMOS mea-surements decide the question which of the two is more correct. The result is that the Total SolarIrradiance value of PMO6-A agrees with TIM/SORCE within its uncertainty and disagrees by morethan ten sigma from VIRGO/SOHO. The initial sensitivity changes of the PREMOS radiometers arestudied using internal assessment and by relative comparison to other operational TSI measurements.The deduced sensitivity changes for PMO6-type instruments in space leads to a re-investigation of theearly VIRGO/SOHO measurements. This re-analysis questions the published trend of the VIRGOTSI values for 1996 and 1997. A new estimate is derived for a TSI trend between the solar minimumin 1996 and the recent minimum in 2008.

E-mail: [email protected]

20 3-7 October 2011 – Mendoza, Argentina

Page 28: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Ni I lines in the Solar Spectrum

M. Vieytes1, P. Mauas1, J. Fontenla2

1IAFE, Argentina2LASP, USA

Abstract. The stratosphere is the region where the ozone chemistry is important for the balanceof energy, and radiation in the near UV plays a fundamental role in the creation and destruction ofozone. However, the radiation in this range of wavelength has not been successfully modeled. One ofthe most important elements, according to its abundance in the solar atmosphere, that contribute tothe emission and absorption of radiation in the spectral range between 1900 and 3900 A, is neutralniquel (Ni I). In this work we improve the atomic model of this element, taking into account 490lines over the spectrum. We solve these lines in NLTE using the Solar Radiation Physical Modeling(SRPM) program and compare the results with observation of the quiet sun spectrum. To investigateif these lines are modified by solar activity we then calculate and compare the same lines with activeregion spectrum.

E-mail: [email protected]

21 3-7 October 2011 – Mendoza, Argentina

Page 29: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Modeling the Solar EUV Variability

M. Haberreiter

PMOD/WRC, Switzerland

Abstract. Solar spectral irradiance variations in the UV/EUV are important for the detailed mod-eling of the Earth’s ionosphere. We present realistic synthetic spectra for this wavelength range.Our approach involves two main steps. First, we calculate the optically thick radiation based ontime-independent 1D atmosphere structures for different activity features of the chromosphere andtransition region. Second, we use 1D coronal atmosphere structures representing various activity fea-tures to calculate the optically thin coronal spectrum. In order to account for the spatial extensionof the corona, we employ a spherical integration scheme for the calculation of the coronal spectrum.The temporal variability of the spectrum is determined from the analysis of solar images. The currentstate of this analysis as well as the potential to reproduce the observed variability will be presented.

E-mail: [email protected]

22 3-7 October 2011 – Mendoza, Argentina

Page 30: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Use of 17 GHz Radio Emission to Characterize the Solar Mini-mum

C. L. Selhorst1, L. Svalgaard2, C. G. Gimenez de Castro3, A. Valio3, J. E. R. Costa4, K. Shibasaki5

1IP&D/UNIVAP, Brazil2HEPL/Stanford University, USA3CRAAM, Brazil4CEA/INPE, Brazil5NoRH, Japan

Abstract. To understand the recent spotless period, we studied the variation of the solar radius andthe polar limb brightening at 17 GHz, comparing the results from the minimum at the end of cycleXXIII with those of the previous one. Daily maps obtained by the Nobeyama Radioheliograph (NoRH)from 1992 through 2010 were analyzed. Whereas the variation of the solar radius at radio frequenciesindicates the heating of the solar atmosphere due to solar activity, the polar limb brightening is highlycorrelated with the local magnetic field intensities (almost 90%). As a common result, it is observeda decrease in both radius and limb brightness intensity at 17 GHz during the present minimum whencompared with the previous one: a) the mean solar radius is 0.9 ± 0.6 arcsec smaller and b) thelimb brightening reduced its intensity by around 20%. Both decrements are interpreted in terms ofthe weaker solar chromospheric activity of the present cycle. Measurement of the radius and limbbrightening at 17 GHz can be used as alternative solar activity index and should be included in theset of parameters used to predict future cycles.

E-mail: [email protected]

23 3-7 October 2011 – Mendoza, Argentina

Page 31: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Polar Magnetic Fields and Coronal Holes during the Recent SolarMinima

G. de Toma


Abstract. The slow decline of solar cycle 23 combined with the slow rise of cycle 24 resulted in avery long period of low magnetic activity during the years 2007-2009 with sunspot number reachingthe lowest level since 1913. This long solar minimum was characterized by weak polar magnetic fields,smaller polar coronal holes, and a relatively complex coronal morphology with multiple streamersextending to mid latitudes. At the same time, low latitude coronal holes remained present on theSun until the end of 2008 modulating the solar wind at the Earth in co-rotating fast wind streams.This magnetic configuration was remarkably different from the one observed during the previous twosolar minima when coronal streamers were confined near the equator and fast solar wind was mainlyoriginating from the large coronal holes around the Sun’s poles. In this talk, we present the evolutionof the polar magnetic fields and coronal holes during the past minimum, compare it with the previousminimum, and discuss the implications for the solar wind near the Earth. In particular, we examinethe changes in the open magnetic flux when the low latitude coronal holes started to close down atthe end of 2008 and finally disappeared in 2009 leading to a simpler heliopheric structure.

E-mail: [email protected]

24 3-7 October 2011 – Mendoza, Argentina

Page 32: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Global Magnetic Fields: Variation of Solar Minima

A. G. Tlatov1, V. N. Obridko2

1Kislovodsk Mountain Astronomical Station of the Pulkovo Observatoy, Russia2Institute of Terrestrial Magnetism, Ionosphere, and Radio Propagation (IZMIRAN), Russia

Abstract. During the activity minimum, the properties of the global magnetic field of the Sunmanifest themselves in the most pronounced way. The magnetic field of the Sun is determined bylarge-scale structures. The northern and southern hemispheres of the Sun have magnetic fields ofopposite polarity. The polar magnetic field is significantly stronger than the fields at middle andlow latitudes in the epoch of minimum activity. In the period of minimum activity, the large-scalestructure of the solar corona also corresponds to the large-scale configuration of solar magnetic fields.The long-term variation of large-scale magnetic fields at different latitudes can be studied using aseries of Hα synoptic charts. The Hα charts contain boundaries on the spherical surface separatingthe positive and negative magnetic polarities. At present, the summary series of Hα charts cover theperiod from 1887 up to now, comparable to the length of the sunspot group series. In this presentation,we consider the indices characterizing the minimum activity epoch according to the data on large-scale magnetic fields and polar activity. These indices are the dipole-octopole index and the area andaverage latitude of the dominant-polarity field in each hemisphere. The indices show that the cycle ofthe large-scale magnetic field of the Sun precedes the sunspot activity cycle by an average of 5.5 years.Analysis of the coronal shape has revealed a long-term modulation of the global magnetic field of theSun. Possibly, a secular modulation of the global solar magnetic field exists, which is most pronouncedduring the epoch of solar activity minimum. During the secular cycle of the global magnetic field ofthe Sun, the relation between the dipole and octopole components of the magnetic field changes. Thelargest amplitude of the dipole component occurred during the interval 1944–1955. At the turn of the19th–20th and 20th–21st centuries, the shape of the solar corona and, possibly, the global magneticfield correspond to the configuration close to that of an octopole.

E-mail: [email protected]

25 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The 3D Solar Minimum Corona with Differential Emission MeasureTomography

A. M. Vasquez1, R. A. Frazin2, Z. Huang2, W. Manchester IV2, P. Shearer2

1Instituto de Astronomıa y Fısica del Espacio (CONICET-UBA) and FCEN (UBA), Argentina2Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, USA

Abstract. Differential emission measure tomography (DEMT) makes use of extreme ultraviolet(EUV) image series to deliver two products: a) the three-dimensional (3D) reconstruction of thecoronal emissivity in the instrumental bands, and b) the 3D distribution of the local differentialemission measure (LDEM). The LDEM allows in turn to construct 3D maps of the electron densityand temperature distribution. DEMT is being currently applied to the space-based EUV imagersSOHO/EIT, STEREO/EUVI, and SDO/AIA, allowing to reconstruct the inner corona in the heightrange from 1.00 to 1.25 Rsun. We have applied DEMT to EUVI data of the last solar minimum (2008),and EIT data of the previous solar minimum (1996). In this talk we will review our results for thedifferent reconstructed rotations, discussing the observed 3D density and temperature distributions inthe context of global potential magnetic field magnetic extrapolations. We will discuss the connectionbetween the DEMT science with other observational and modeling efforts of the same periods.

E-mail: [email protected]

26 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Solar Cycle 23 and 24 Minima Seen through the Eyes of CoronalMHD Models

J. Linker, Z. Mikic, P. Riley, R. Lionello, V. Titov

Predictive Science, Inc., USA

Abstract. The mimima preceding solar cycle 24 is characterized by unusual properties when comparedwith the previous cycle and other space age minima. These features include many more spotless days,weaker polar magnetic field strengths, weaker interplanetary magnetic fields, and persistent isolatedequatorial coronal holes. We compare 3D MHD simulations of the corona during these two intervalsto explore the detailed characteristics of the corona during these different time periods. We discusshow the recent unusual minima provides opportunities to test our understanding of the underlyingprocesses that produce the corona and solar wind, particularly the origin of the slow solar wind.

Research supported by NASA and NSF.

E-mail: [email protected]

27 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Large-Scale Photospheric Flow Patterns around Coronal Structures

N. Hurlburt

Lockheed Martin Advanced Technology Center, USA

Abstract. Large-scale photospheric flows in the vicinity of coronal structures are investigated. Weidentify a set of filaments, active regions and coronal holes recorded in the Heliophysics Events Knowl-edgebase (HEK) over the first year of SDO operations. We use these lists to select subsets of HMIand AIA data for further analysis. Surface velocities are extracted from data cubes using a spectraloptical flow method and are compared with the characteristics of the corresponding features.

E-mail: [email protected]

28 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Assessing Modern Magnetographs and Spectropolarimeters

J. C. del Toro Iniesta1, V. Martınez Pillet2

1IAA-CSIC, Spain2IAC, Spain

Abstract. The design and later use of modern spectropolarimeters and magnetographs require anumber of tolerance specifications that allow the developers to build the instrument and then thescientists to interpret the data accurately. Such specifications depend both on device-specific featuresand on the physical assumptions underlying the particular measurement technique. Here we discussgeneral properties of every magnetograph, as the detectability thresholds for the vector magnetic fieldand the line-of-sight velocity, as well as specific properties of a given type of instrument, namely thatbased on a pair of nematic liquid crystal variable retarders and a Fabry-Perot etalon (or several) forcarrying out the light polarization modulation and spectral analysis, respectively. We derive formulaethat give the detection thresholds in terms of the signal-to-noise ratio of the observations and thepolarimetric efficiencies of the instrument. Relationships are also established between inaccuraciesin the solar physical parameters and instabilities in the instrument parameters. Such relationshipsallow, for example, to translate scientific requirements for the velocity or the magnetic field intorequirements for temperature or voltage stability. We also demonstrate that this type of magnetographcan theoretically reach the optimum polarimetric efficiencies of an ideal polarimeter, regardless of theoptics in between the modulator and the analyzer. Such optics induces changes in the instrumentparameters that are also calculated.

E-mail: [email protected]

29 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Structure of the Heliosphere in Solar Minima and Consequenceson Interplanetary Flux Rope Properties

S. Dasso1,2, A. M. Gulisano1,2, P. Demoulin3

1Instituto de Astronomıa y Fısica del Espacio (UBA-CONICET), Argentina2Departamento de Fısica, Facultad de Ciencias Exactas y Naturales (UBA), Argentina3Observatoire de Paris, LESIA, Meudon, France

Abstract. The study of the heliosphere has advanced greatly in the last few years. Comparisonsbetween models and observations are clarifying several issues of this system. The synergy from com-bining modelling with different observational techniques have produced very important progresses inour understanding of different objects in the heliosphere, with important consequences on Sun-Earthconnection and space weather. It is well known that the structure of the heliosphere depends onthe solar cycle stage, presenting its simplest global organization during solar minima. Then, studiesof the heliosphere in periods of solar minima provide good oportunities to improve our understand-ing of the three dimensional structure of the heliosphere. These periods are also natural places tostudy the manifestation of ’less mixed’ physical processes and their consequences on the evolutionof transient objects traveling along relatively clean environments, which are generally present duringsolar minima. A comparative study of solar wind properties during two solar minima periods will besummarized in this talk, with emphasis on properties and dynamical evolution of interplanetary fluxropes propagating in periods with similar characteristics.

E-mail: [email protected]

30 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Coronal Transients During two Solar Minima: Their Solar SourceRegions and Interplanetary Counterparts

H. Cremades1, C. H. Mandrini2, S. Dasso2

1FRM-UTN/CONICET, Argentina2IAFE, CONICET, Argentina

Abstract. In the frame of two coordinated observational and research efforts, two full solar rotationswere investigated in times of two distinct solar minima. These two campaigns were dubbed Whole SunMonth (WSM; August 10 - September 8, 1996) and Whole Heliosphere Interval (WHI; March 20 - April16, 2008). The nearly uninterrupted gathering of solar coronal data since the beginning of the Solarand Heliospheric Observatory (SOHO) era offers the exceptional possibility of comparing two solarminima for the first time, with regard to the coronal transient aspect. This study characterizes thevariety of outward-travelling transients observed in the solar corona during both time intervals, fromvery narrow jet-like events to coronal mass ejections (CMEs). Their solar source regions and ensuinginterplanetary structures were identified and characterized as well, towards a global-scale descriptionof their role in determining the heliosphere’s conditions. Multi-wavelength images provided by thespace missions SOHO, Yohkoh (only WSM), and Solar-Terrestrial Relations Observatory (STEREO;only WHI) and ground-based observatories were analyzed for coronal ejecta and their solar sources,while data registered by the Advanced Composition Explorer (ACE) spacecraft were inspected forinterplanetary CMEs and magnetic clouds. Notable differences arise from the analysis of the detailedsurvey of events: more (less) ejecta during WHI (WSM), 12% (40%) were produced by active regionsduring WHI (WSM), and nearly no (high) deflection from the radial direction was observed during WHI(WSM). Instrumental aspects such as dissimilar resolution, cadence, and fields of view are consideredin order to discern instrumentally-driven disparities from inherent differences between solar minima.

E-mail: [email protected]

31 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Role of Streamers in the Deflection of Coronal Mass Ejections:Comparison between STEREO 3D Reconstructions and NumericalSimulations

F. P. Zuccarello1, A. Bemporad2, C. Jacobs1, M. Mierla3, S. Poedts1, F. Zuccarello4

1KULeuven, Belgium2INAF, Italy3ROB, Belgium4UCT, Italy

Abstract. On September 21, 2009 a Coronal Mass Ejection (CME) was observed by the coronographson board the STEREO spacecraft. The CME originated from the southern hemisphere and showed adeflection of more than 30 degrees towards the heliospheric current sheet (HCS) during the propagationin the COR1 field-of-view (FOV). The aim of this paper is to provide a physical explanation for thestrong deflection of the CME observed on September 21, 2009. The two-sided view of the STEREOspacecraft allows to reconstruct the three dimensional (3D) travel path of the CME and the evolutionof the CME source region. The observations are combined with a MHD simulation, starting froma magnetic field configuration closely resembling the extrapolated potential field for that date. Byapplying localized shearing motions a CME is initiated in the simulation, showing a similar non-radialevolution, structure, and velocity as the observed event. The CME gets deflected towards the currentsheeth of the larger northern helmet streamer, due to an imbalance in the magnetic pressure andtension forces and finally it gets absorbed into the streamer. This study shows that during solarminima, even CMEs originating from high latitude can be easily deflected towards the heliosphericcurrent sheet eventually resulting in geoeffective events. How rapidly they undergo this latitudinalmigration depends on the strength of both the large scale coronal magnetic field and the magneticflux of the erupting filament.

E-mail: [email protected]

32 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Dynamo-driven Plasmoid Ejections above a Spherical Surface

J. Warnecke1,2, A. Brandenburg1,2, D. Mitra1

1NORDITA, Sweden2Department of Astronomy, Stockholm University, Sweden

Abstract. We extend earlier models of turbulent dynamos with an upper, nearly force-free exteriorto spherical geometry, and study how flux emerges from lower layers to the upper ones without beingdriven by magnetic buoyancy. We also study how this affects the possibility of plasmoid ejection. Aspherical wedge is used that includes northern and southern hemispheres up to mid-latitudes and acertain range in longitude of the Sun. In radius, we cover both the region that corresponds to theconvection zone in the Sun and the immediate exterior up to twice the radius of the Sun. Turbulence isdriven with a helical forcing function in the interior, where the sign changes at the equator between thetwo hemispheres. An oscillatory large-scale dynamo with equatorward migration is found to operatein the turbulence zone. Plasmoid ejections occur in regular intervals, similar to what is seen in earlierCartesian models. These plasmoid ejections are tentatively associated with coronal mass ejections.The magnetic helicity is found to change sign outside the turbulence zone, which is in agreement withrecent findings for the solar wind.

E-mail: [email protected]

33 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Dynamic Evolution of Interplanetary Wave Shocks Driven by CMEs

P. Corona Romero1, J. A. Gonzalez Esparza2

1Posgrado en Ciencias de la Tierra, UNAM, Mexico2Instituto de Geofısica, UNAM, Mexico

Abstract. We present a study of the dominant physical processes of the CME/shock evolution usingan analytic model and numerical simulations. We find that shock waves related with fast CMEspresent two phases: a pristine one where the CME drives the shock, followed by a decaying phasewhere the shock decelerates. This dynamical behavior depends on the evolution of the momentumflux throughout the plasma sheath, which illuminates the CME/shock propagation. We analyze threestudy cases in order to apply our results. This work is an extension of the Corona-Romero & Gonzalez-Esparza [JGR, 2011] study of CME/shock propagation focusing, in this case, on the evolution of theplasma sheath between the CME and the shock.

E-mail: [email protected]

34 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Dynamical Evolution of Anisotropies of the Solar Wind MagneticTurbulent Outer Scale

M. E. Ruiz1, S. Dasso1,2, W. H. Matthaeus3, E. Marsch4, J. M. Weygand5

1Instituto de Astronomıa y Fısica del Espacio (CONICET-Universidad de Buenos Aires), Argentina2Departamento de Fısica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires,Argentina3Department of Geography, Bartol Research Institute, University of Delaware, USA4Max-Planck-Institut fur Sonnensystemforschung, Germany5Institute of Geophysics and Planetary Physics, University of California, USA

Abstract. The evolution of the turbulent properties in the solar wind, during the travel of the parcelsof fluid from the Sun to the outer heliosphere still has several unanswered questions. In this work, wewill present results of an study on the dynamical evolution of turbulent magnetic fluctuations in theinner heliosphere. We focused on the anisotropy of the turbulent length scale, measured parallel andperpendicular to the direction of the local mean magnetic field, and study its evolution according tothe aging of the plasma parcels observed at different heliodistances. As diagnostic tool we employedsingle-spacecraft correlation functions computed with observations collected by Helios 1 & 2 probesover nearly one solar cycle. Our results are consistent with driving modes with wave-vectors parallelto the direction of the local mean magnetic field near the Sun, and a progressive spectral transfer ofenergy to modes with perpendicular wave-vectors. Advances made in this direction, as those presentedhere, will contribute to our understanding of the magnetohydrodynamical turbulence and Alfvenic-wave activity for this system, and will provide a quantitative input for models of charged solar andgalactic energetic particles propagation and diffusion throughout inner heliosphere.

E-mail: [email protected]

35 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Interplanetary Conditions: Lessons from this Minimum

J. G. Luhmann1, C. O. Lee1 , P. Riley2, L. K. Jian3, C. T. Russell3, G. Petrie4

1SSL, University of California, USA2PSI, USA3IGPP UCLA, USA4NSO, USA

Abstract. We use results from studies of the solar wind in the recent cycle minimum as a basisfor discussing how the interplanetary medium attributes are determined by the solar magnetic field.In particular, the complexity of the coronal field at the effective source surface of the solar wind incycle 23’s minimum, discussed by de Toma et al. earlier, means that it is common for a magneticpolarity sector to have streams from several source regions, all of which have somewhat differentproperties. As a result, the wind of a given polarity may include stream interaction regions thatare not associated with heliospheric sector boundaries. One of the consequences of this situationis that stream interaction compressions and their associated field deflections and enhancements aremore common than in the dipolar coronal hole wind picture. Another is that transient coronal holeboundary layer winds are ubiquitous within a magnetic sector. This characteristic produces a hostof substructure in the solar wind that is challenging to interpret. Overall, the recent cycle minimumprovides an excellent illustration of the need for more realistic coronal field geometries in 3D solarwind models, allowing for time dependent processes at open field boundaries. It also serves to remindus that simple solar wind concepts often fail to capture the reality of stellar outflows.

E-mail: [email protected]

36 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Floor in the Solar Wind Magnetic Field: Status Report

E. W. Cliver


Abstract. The notion of a ”floor” in the solar magnetic field strength (Bsw) of ∼4.6 nT was proposedby Svalgaard and Cliver in 2007 on the basis of 27-day averages of Bsw during the space age and long-term reconstructions of Bsw based on geomagnetic data. In both 2008 and 2009, the concept of sucha floor was undercut by annual Bsw averages of ∼4 nT. Subsequently, Cliver and Ling (2010) revisedthe floor downward to ∼2.8 nT on the basis of separate correlations between the solar polar fieldstrength at solar minimum and (a) the corresponding solar wind magnetic field strength (Bsw(min))and (b) the peak sunspot number at the subsequent solar maximum. These correlations suggest thatat 11-year minima, B consists of i) a floor of ∼2.8 nT, and ii) a component primarily due to thesolar polar fields that varies from ∼0 nT to ∼3 nT. The solar polar fields provide the ”seed” for thesubsequent sunspot maximum. Based on a decomposition of the solar wind (from 1972 - 2009) intohigh-speed streams, coronal mass ejections, and slow solar wind, Cliver and Ling suggested that thesource of the floor in Bsw is the slow solar wind. During 2009, Earth was in slow solar-wind flows∼70% of the time. Cliver and Ling attributed the floor to a baseline (non-cyclic or ground state) opensolar flux of ∼ 8 × 1013 Wb from the Sun’s persistent small-scale (supergranular and granular) field.Recent evidence bearing on the possibility of the floor is reviewed.

E-mail: [email protected]

37 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Long-term Solar Wind Variations and the Coming Solar Minimum

R. E. Lopez

Department of Physics, University of Texas at Arlington, USA

Abstract. In this talk I will discuss long-term solar wind variations, with an emphasis on the variationof the solar wind around successive minima. Throughout the latter half 20th century, the period whenin situ observations are available, the mass, momentum, and energy fluxes of the solar wind along withthe IMF magnitude were increasing from one solar cycle to the next. This changed in solar cycle 23,when all indicators of solar wind strength decreased. The minimum at the boundary between solarcycles 23 and 24 exhibited the weakest solar wind in the observational record. At the same time,the ratio of the flux of alpha particles to the proton flux decreased markedly, and the relationshipbetween the alpha particle flux and the IMF, which had been fairly stable for the previous solarcycles, changed dramatically. These changes strongly imply that something fundamental has changedin the solar cycle, that the Modern Grand Maximum is at an end, and that a long-term minimum insolar activity has begun.

E-mail: [email protected]

38 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Probing the Heliosphere with the Directional Anisotropy of GalacticCosmic Ray Intensity

K. Munakata

Shinshu University, Japan

Abstract. Galactic cosmic rays are extremely high-energy nuclei that travel close to the speed oflight. They are ubiquitous in the Milky Way and make up a substantial fraction of the total energy ofthe Galaxy, equivalent to the energy in large-scale magnetic fields and thermal gases. Being chargedparticles, they are deflected when crossing the magnetic field in the space, and the amount of the totaldeflection in an average magnetic field magnitude is dependent on both their momentum and pathlengths. The cosmic-ray flux at energies high enough to undergo minimal deflection is so small thatcosmic-ray sources in the Galaxy far away from us have proved difficult to observe directly by measuringthe directional anisotropy of GCR intensity. The significant deflection and the pitch angle scatteringby the irregular magnetic field produces instead the diffusive streaming which has been observed asthe GCR anisotropy at the Earth with the amplitude of ∼0.1%. The present paper demonstrateshow useful information can be derived from the anisotropy observed at the Earth with ground baseddetectors. The intensity of ∼10 GeV galactic cosmic rays recorded at the Earth changes in the solaractivity- and magnetic-cycles reflecting the solar cycle variations of the modulation parameters suchas the sun-spot number, the magnitude of the interplanetary magnetic field and the tilt-angle of theheliospheric current sheet. The best-known example of such variation can be seen in the count rate ofneutron monitors. While the omnidirectional GCR intensity measured by a single detector representsthe temporal variation of the GCR density at the single location of the detector, the directionalanisotropy of the GCR intensity tells us the spatial distribution of the GCR density around theEarth. The magnitude of the GCR anisotropy due to the diffusive streaming is proportional to thespatial gradient of the GCR density. By observing precisely the anisotropy with the global network ofdetectors, therefore, we can derive the spatial gradient of the GCR density in three dimensions and itstemporal variation. The spatial density gradient is important, because it tells us the average featureof the large-scale magnetic field in the heliosphere which is responsible to the spatial distribution ofGCRs. Is still difficult to derive it directly from any other in-situ and/or ground-based measurements.In this paper, we analyze the density gradient and its temporal variation observed with two networks ofmuon detectors and neutron monitors during the declining phase of the Solar Cycle 23. The anisotropyof GCRs with much higher energy also provides us with unique information of the magnetic field overthe larger scale in space. The sidereal anisotropy of ∼TeV GCRs observed by the air shower (AS)experiment and deep underground muon detectors gives us the valuable information of the large-scalemagnetic structures of the heliosphere and the local interstellar space near by the Sun. The presentpaper also demonstrates a possibility of probing the Sun’s magnetic field as a function of time with themeasurement of the Sun’s shadow. The Sun shields cosmic rays arriving from the directions behind itand casts a tiny shadow in the directional intensity of cosmic rays observed at the Earth. The TibetAS experiment has recently observed a clear solar cycle variation of the Sun’s shadow for the firsttime. The present paper introduces the recent analyses of the Sun’s shadow observed by the TibetAS experiment.

E-mail: [email protected]

39 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Search for Solar Energetic Particle Signals on the Mexico City Neu-tron Monitor Database

B. Vargas, J. F. Valdes Galicia

Instituto de Geofısica, UNAM, Mexico

Abstract. We made a search for solar energetic particle signals on the full five minute database ofthe Mexico City neutron monitor from 1989 to 2006. Daubechies filters were used to set a baselineand remove unwanted low frequency variations; then, we performed two different statistical tests tovalidate the increments observed on the data. We present a detailed analysis of one GLE time serieswhich shows a previously unreported increment. Due to the high cutoff rigidity of the site (8.27 GV)and mean response energy of the instrument (25 GeV), this result provides evidence of accelerationof high energy particles by eruptive phenomena in the solar atmosphere; our analysis may also helpto establish an upper bound for the particle acceleration power of the Sun.

E-mail: [email protected]

40 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

On the Cause of Extremely Low Geomagnetic Activity during theRecent Deep Solar Cycle Minimum

E. Echer1, B. T. Tsurutani1,2, W. D. Gonzalez1

1Instituto Nacional de Pesquisas Espaciais, Brazil2Jet Propulsion Laboratory, California Institute of Technology, CA

Abstract. The recent solar minimum (2008–2009) was extreme in several aspects: the sunspotnumber, interplanetary magnetic field (IMF) magnitude and solar wind speed were the lowest duringthe space era. Furthermore, the exceedingly low solar wind parameters led to a minimum in energytransfer from solar wind to the magnetosphere, and as a consequence, the geomagnetic activity apindex reached extremely low levels. These were the lowest values of energy input and geomagneticactivity in the space era. We compare the solar wind and geomagnetic activity observed in this recentminimum with previous solar cycle values during the space era (1964–2010).

E-mail: [email protected]

41 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

WHI in the Context of a Long and Structured Solar Minimum: AnOverview of Sun-to-Earth Observations

S. E. Gibson1 , G. de Toma1, Y. Elsworth2 , B. Emery 1, R. Leamon3, J. Lei4, S. McIntosh1, R.Mewaldt5 , T. Onsager6, B. J. Thompson7, P. Riley8, L. Zhao1

1HAO/NCAR, USA2Univ. Birmingham, UK3NASA, USA4Univ. Colorado, USA5CalTech, USA6NOAA/SWPSI, USA7NASA/GSFC, USA8PredSci, USA

Abstract. Throughout months of extremely low solar activity during the recent extended solar cycleminimum, structural evolution continued to be observed from the Sun through the solar wind andto the Earth. In 2008, the presence of long-lived and large low-latitude coronal holes meant thatgeospace was periodically impacted by high-speed streams, even though solar irradiance, activity, andinterplanetary magnetic fields had reached levels as low or lower than observed in past minima. Thistime period – of which the Whole Heliosphere Interval (WHI: CROT 2068) is typical – illustrates theeffects of fast solar wind streams on the Earth in an otherwise quiet heliosphere. By the end of 2008sunspots and solar irradiance had reached their lowest levels for this minima (e.g., CROT 2078), andcontinued solar magnetic flux evolution had led to a flattening of the heliospheric current sheet andthe decay of the low-latitude coronal holes and associated Earth-intersecting high-speed solar windstreams. This simplified heliospheric morphology was associated with record levels of cosmic rays(high) and radiation belt flux (low). As the new solar cycle slowly began, solar wind and geospaceobservables stayed low or continued to decline, reaching a minimum in summer 2009 (e.g. CROT 2085)and a Sun-Earth system at its quietest. In this poster we will present an overview of observationsthat span the period 2008–2009, with highlighted discussion of CROTs 2068, 2078, and 2085. We willshow side-by-side observables from the Sun’s interior through its surface and atmosphere, through thesolar wind and heliosphere and to the Earth’s space environment and upper atmosphere.

E-mail: [email protected]

42 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Modeling of the Atmospheric Response to a Strong Decrease of theSolar Activity

E. Rozanov1,2, T. Egorova1, A. Shapiro1, W. Schmutz1

1PMOD/WRC,Switzerland2IAC ETHZ, Switzerland

Abstract. It was suggested by several publications that the current grand maximum of the solaractivity will end within the next 10 to 20 years. Such a change can affect future state of the atmosphereand climate due to an alteration of the incoming solar irradiance and energetic particles. On the onehand a decline of the solar activity is expected to be accompanied by a decrease of the spectral solarirradiance leading to cooling and ozone depletion in the stratosphere, a deceleration of the polar nightjets and cooler winters over Europe. These effects will be partially compensated by an expecteddecrease of the geomagnetic activity and less intensive production of nitrogen and hydrogen oxidesfollowed by less intensive ozone destruction and relative warming inside polar vortices. On the otherhand an increase of galactic cosmic rays caused by lower solar activity will facilitate ozone destructionand cooling in the polar lower winter stratosphere leading to opposite effects, i.e. to an accelerationof the polar night jets and warmer winters over Europe. To understand the resulting changes inthe atmosphere we perform several numerical experiments with chemistry-climate model SOCOL intime-slice mode driven by different combinations of the above-mentioned forcing. The results of theseexperiments aimed at the analysis of ”top-down” mechanisms of solar-climate connection as well asthe uncertainty in the applied forcing will be presented and discussed in the talk.

E-mail: [email protected]

43 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Ionosphere and Upper Atmosphere under the Extremely ProlongedLow Solar Activity of Solar Cycle 23/24

I. S. Batista1, C. M. N. Candido1, C. Brum2, M. A. Abdu1

1INPE, Brazil2Arecibo Observatory, Puerto Rico

Abstract. The solar irradiance at extreme ultraviolet (EUV) wavelengths is the primary heat sourceof the thermosphere. The thermosphere responds to temperature changes expanding or contractingin such a way that the thermospheric density, at a fixed height is highly dependent on the solar EUVflux. The solar radiation is also the responsible for the ionospheric primary ionization and its layeringstructure. During the minimum of the solar cycle 23/24 the sun had a large number of spotless daysas compared with previous periods. During this unusually prolonged solar minimum the solar fluxresponsible for the thermospheric heating and ionospheric formation was very low. This provideda unique opportunity for the investigation of the thermosphere-ionosphere system under extremelylow solar activity. Studies are indicating the need to review some proxies used to represent the solarirradiance in thermosphere-ionosphere models. The low density ionosphere has also provided goodconditions for the study of waves propagating in the ionospheric F region.

E-mail: [email protected]

44 3-7 October 2011 – Mendoza, Argentina

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Session 4

Stellar Cycles


Cristina MandriniAdriana Valio

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Stellar Cycles: General Properties and Future Directions

M. Giampapa

National Solar Observatory/NOAO, USA

Abstract. I will review the general properties of stellar cycles in late-type, main sequence starsincluding the range of amplitudes seen in solar-type stars, the associated brightness variations, andthe evidence for stars in activity minima that may be analogous to the extended episode of quiescenceassociated with the Maunder minimum. Emerging evidence for the occurrence of multiple cycle periodsin solar-type stars will be reviewed as well as the nature of ”flat-activity” stars. Suggested directionsfor future efforts will be presented.

The NSO and NOAO are each operated by AURA under cooperative agreements with the NationalScience Foundation.

E-mail: [email protected]

46 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Investigating Stellar Surface Rotation using Observations of Starspots

H. Korhonen

NBI, Denmark

Abstract. Rapid rotation enhances the dynamo operating in stars, and thus also introduces signif-icantly stronger magnetic activity than is seen in slower rotators. Many young cool stars are rapidrotators, because they have the primordial rotation rates induced by the interstellar molecular cloudfrom which they were formed. Also older stars in close binary systems are rapid rotators. These typesof stars can show strong magnetic activity and large starspots. In the case of large starspots whichcause observable changes in the brightness of the star, and even in the shapes of the spectral lines,one can get information on the rotation of the star. At times even information on the spot rotationat different stellar latitudes, similarly to the solar surface differential rotation, can be obtained. Inthis talk I will review investigations of stellar rotation based on starspots. I will discuss what we canobtain from ground-based photometry and how that improves with the uninterrupted, high precision,observations from space. The emphasis of the talk will be on how starspots, and even stellar surfacedifferential rotation, can be studied using shapes of the spectral lines in high resolution spectra.

E-mail: [email protected]

47 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Modulated Stellar and Solar Cycles: Parallels and Differences

K. Olah1, L. van Driel-Gesztelyi1,2,3

1Konkoly Observatory, Hungary2MSSL, University College London, UK3Paris Observatory, LESIA, Meudon, France

Abstract. We present examples of activity cycles on different types of stars from low-mass dwarfsto massive giants with a range of rotational rates, and compare the observed cyclic behaviors to thesolar cycle and its modulations as manifested in long-term reconstructed solar irradiance data. Usingsolar irradiance data - i.e. emitted flux - a direct comparison can be made between solar and stellarcycles. Furthermore, a diagnostics of different features dominating the activity on stars causing theirlong-term variability becomes possible. In the course of their activity cycles stars change their overalltemperature, which is measured through the variation of the color indices. In the case when activityis dominated by spots, i.e. cooler surface features, the star is redder when fainter, whereas anothertype of activity makes the stars hotter when activity is higher. We show examples for both classes,including the Sun, which belongs to the latter group.

E-mail: [email protected]

48 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Solar Wind in Time: Internal and External Forcing

J. L. Linsky1, B. Wood2, S. Redfield3

1Univ. Colorado, USA2NRL, USA3Wesleyan Univ., USA

Abstract. Changes in the solar wind structure and mass flux between minimum and maximum ofthe solar cycle are likely small compared to changes in the solar wind as the Sun has evolved from anactive premain sequence star to its present middle age as a slowly-rotating rather quiet star. We willdescribe our technique of inferring wind mass loss rates for solar-like stars and show correlations ofmass flux with X-ray emission and stellar age. This technique will be applied to additional stars inour HST Cycle 19 observing programs. The gas density and magnetic field of the interstellar mediumthrough which the Sun moves provide external boundary conditions on the solar wind. We now havea detailed picture of the interstellar cloud environment through which the Sun has travelled for thelast million years and will travel for the next million years. Changes in the gas density and magneticfield environment through which the Sun travels will likely force changes in the solar wind on a fastertimescale than secular changes in the solar dynamo and magnetic field. Simulations of wind massflux for solar-like stars provides a critical tool for understanding the chemical evolution of planetaryatmospheres both for planets of our Sun and of other stars. An important example is the loss of waterfrom Mars.

E-mail: [email protected]

49 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Stellar Activity Cycles in a Model for Magnetic Flux Generation andTransport

E. Isik

Istanbul Kultur University, Turkey

Abstract. As solar and stellar observations of magnetic cycles improve both in quantity and quality,it becomes essential to investigate the physical mechanisms behind the observed (multi-)periodic orirregular stellar cycles. We present results from a model of magnetic flux generation and transport incool stars (Isik et al. 2011 A&A 528, A135), which combines an alpha-omega dynamo at the base ofthe convection zone, buoyant rise of magnetic flux tubes, and a surface flux transport model. Basedon a reference model for the Sun, the numerical simulations were made for a set of model convectionzones of G- and K-type main sequence and subgiant stars. We investigate magnetic cycle properties asfunctions of other stellar properties such as the rotation period, convection zone depth, and dynamostrength. For a Sun-like star with Prot = 9 d, we find that a cyclic dynamo can underly a non-cyclic, ”flat” surface activity. For a subgiant K1 star such as the active component of HR 1099, anapparently multi-periodic cycle (similar to observations; eg Olah et al. 2009 A&A 501, 703) is foundin our model, owing to a combination of several effects: cycle overlap, poleward deflection of risingflux tubes, convection zone depth, and surface flux transport.

E-mail: [email protected]

50 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Magnetic Activity among Cool Stars in the HR-Diagram

J. H. M. M. Schmitt

Hamburger Sternwarte, Germany

Abstract. Magnetic fields are the ultimate origin of the plethora of activity phenomena observedon the Sun over the entire electromagnetic range. Soft X-ray emission diagnoses hot, thermal plasmaheated to coronal temperatures and is the best proxy indicator for such magnetic activity since it canbe detected against a completely X-ray dark stellar photosphere. UV- and optical emission diagnosescooler plasma and the photospheric magnetic fields themselves, however, applicability and usefulnessof these indicators depends strongly on the underlying star. Nonthermal emission is diagnosed at radioand Gamma-ray wavelengths and can usually be detected only in stars with activity levels some ordersof magnitude above solar levels. I will attempt to review the magnetic activity signatures observed inthe cool half of the HR-diagram predominantly from an X-ray point of view to delineate which starsshow magnetic activity. I will then focus on the properties of stars with low activity and specificallydiscuss the the rotation activity relations, the occurrence of magnetic cycles and the detectabilityof Maunder minimum states in other stars. Finally, cool stars are hosts of extrasolar planets and Idiscuss some consequences of cool star activity on extrasolar planets.

E-mail: [email protected]

51 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

On the Origin of Stellar Magnetic Fields

R. Steinitz1, J. Portnoy2

1Physics, Ben Gurion University, Israel2EE Dept., Sami Shamoon Acad. College of Engineering, Israel

Abstract. The origin of stellar magnetic fields is not a new problem. Our approach is three-pronged:(a) Observed enormous diversity of spectral types as well as space locations of magnetic stars, (b) the(relative) rarity of such stars, and most relevant - (c) the basic physics involved in spoiling cylindricalsymmetry (magnetic dipole and spin axis not co-aligned). The emerging model accounts for thesetraits; in addition it predicts existence of large ranges in field intensities on different magnetic stars,possible presence of magnetic quadrupoles and that at least some magnetic stars are oscillating; allpredictions observed.

E-mail: [email protected]

52 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Semi-empirical Modeling of Solar/Stellar Magnetic Cycles

A. Valio

CRAAM/Mackenzie University, Brazil

Abstract. Since Galileo, for four hundred years, dark spots have been observed systematically onthe surface of the Sun. The monitoring of the sunspot number has shown that their number variesperiodically every 11 years. This is the well known solar activity cycle, and is caused by the periodicchanges of the magnetic field of the Sun. Not only do spots vary in number on a timescale of a decade,but the total luminosity and other signatures of activity such as flares and coronal mass ejectionsalso increase and decrease with the 11-year cycle. Still unexplained to the present date are periodsof decades with almost an absence of activity, where the best known example of such is the MaunderMinimum. Other stars also exhibit signs of cyclic activity, however the level of activity is usuallythousand times higher than the solar. Obviously, this is due to the difficulty of observing activity atthe solar level on most stars. Presently, a method has been developed to detect and study individualsolar like spots on the surface of planet-harboring stars. As the planet eclipses dark patches on thesurface of the star, a detectable signature can be observed in the light curve of the star during thetransit. The study of a different variety of stars allows for a better understanding of magnetic cyclesand the evolution of stars.

E-mail: [email protected]

53 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Rotation-activity Connection in Young Low Mass Stars

J. Rodrıguez Gomez, O. Restrepo Gaitan, R. M. Cuervo Osses, G. Pinzon Estrada

Observatorio Astronomico, Facultad de Ciencias, Universidad Nacional de Colombia, Colombia

Abstract. Rotation and activity are key parameters for the pre-main sequence evolution since theytrace the internal behavior of young stars as they approach to the main sequence and also becausethey are closely related to the disk disappearance and the presence of solar-type active chromospheres.Nearby associations or moving groups of post-T Tauri stars with ages between 10 and 30 Myr areexcellent targets for the study of both, rotation and activity. We present a complementary study tothose presented by Sholtz et al.(2007) of rotation, chromospheric activity and X-ray luminosities for asample of 71 young stars with spectral types F7–M2 in the stellar associations: TW Hya (∼10Myr),BPMG (∼11Myr), Upper Centaurus Lupus (∼14Myr), Lower Centarus Crux (∼16Myr) and Tucana-Horologium (∼30Myr). We confirm a mass dependence of the lifetime for active chromospheres andfound that the chromospheric activity measured in Hα declines with age. The rotation-activity relationshows prominent differences with those observed in main sequence stars indicating that young low massstars generate their magnetic fields in a different way (not dynamo). We quantify those differencesby comparing either vsini or rotational periods with a simple rotational evolution model based on thetemporal behaviour of the size of the convective layers predicted by evolutionary PMS models.

E-mail: [email protected], [email protected]

54 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

12 Years of Stellar Activity Observations in Argentina

P. Mauas1, A. Buccino1, R. Dıaz2, C. Cincunegui1, M. L. Luoni1

1Instituto de Astronomıa y Fısica del Espacio, Argentina2Institut d’Astrophysique de Paris, France

Abstract. Since 1999 we systematically observe around 150 stars, from late F to M, to study long-term variability. For this task we used the echelle spectrograph mounted in the 2.15m telescope atCASLEO Observatory in San Juan, Argentina, covering the range 3860 to 6690 Awith a spectralresolution R=13000. From these data, we were able to find cyclic activity in several M stars, includingProxima Centauri. These spectra was also used to constrain chromospheric models of several G andK stars, to understand how changes in activity affect the atmospheric structure.

Since, unlike other similar studies, we have simultaneous measurements of the most important visiblelines, we can accurately study the correlation between them. For example, the H-α and Ca II K fluxesare usually considered interchangeable activity indicators, and in fact we found a strong correlationbetween the mean fluxes for each star. However, the general trend is lost for individual observationsof particular stars, and each star shows a particular behavior, ranging from tight correlations withdifferent slopes to anti-correlations, including cases where no correlations are found.

At present, we have a very large database, with more than 2000 spectra of the whole visible range, ofstars of a broad variety of spectral classes, with different activity levels, and spanning 12 years.

E-mail: [email protected]

55 3-7 October 2011 – Mendoza, Argentina

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Session 5

Grand Minima and Historical Records


Alisson Dal Lago

Ilya Usoskin

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Stars in Magnetic Grand Minima: Where Are They and What AreThey Like?

S. H. Saar


Abstract. I explore various ideas of what a star in a Maunder-like magnetic minimum would looklike, and ways of finding stars in such a state, and make some estimates of their physical and magneticactivity properties. These are then compared with the Sun and other low activity stars.

E-mail: [email protected]

57 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Soft X-ray Emission as Diagnostics for Maunder Minimum Stars

K. Poppenhager, J. H. M. M. Schmitt

Hamburger Sternwarte, Germany

Abstract.The identification of stars in a Maunder minimum state purely from their chromosphericemission (for example in Ca II lines) has proven to be difficult. Photospheric contributions, metallici-ties and possible deviations from the main sequence stage may lead to very low values of the traditionalchromospheric activity indicators, while no Maunder minimum state may be present. X-ray obser-vations can be a key tool for identifying Maunder minimum stars: we have detected very soft X-rayemission from low-temperature coronal plasma, similar to emission from solar coronal holes, in severalstars with very low chromospheric activity indicators. The coronal properties inferred from X-rayobservations can therefore yield a crucial piece of information to verify Maunder minimum states instars.

E-mail: [email protected]

58 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Is the Small-Scale Quiet Sun Dynamo a Pedestal for Solar (and Stel-lar) Activity?

K. J. Schrijver

Lockheed Martin Advanced Technology Center, USA

Abstract. Surrounding the sunspot-carrying active regions lies a sea of small-scale mixed-polarity”quiet Sun”. Part of the magnetic flux threading that quiet Sun results from the random-walk dispersaland large-scale advection of flux that originally surfaced in active regions. Observations during therecent extended sunspot minimum, combined with four decades of monitoring of the quietest regionson the solar disk, suggest, however, that there is a cycle-independent component to the quiet-Sun field(doi:10.1029/2011GL046658) that persists at times of extended cycle minima and Maunder Minimum-like ’grand minima’. The implications for TSI coupling into Earth’s climate are being investigated.Here, I place these observations in the context of stellar magnetic activity and, in particular, theinterpretation of the minimal activity, at the basal emission level, of old Sun-like stars.

E-mail: [email protected]

59 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Interplanetary Space Weather and Space Climate Prediction: Op-portunities

M. Guhathakurta

NASA Headquarters, USA

Abstract. As human activity expands into the solar system, the need for accurate space weatherand climate forecasting is expanding, too. Space probes are now orbiting or en route to flybys ofMercury, Venus, Earth and the Moon, Mars, Vesta, Ceres, Saturn, and Pluto. As agencies around theworld prepare for these missions to send robotic spacecraft, each of these missions (plus others on thedrawing board) has a unique need to know when a solar storm will pass through its corner of spaceor how the subsequent solar cycles will behave. Ultimately, astronauts will follow beyond Earth orbit,and their need for interplanetary space weather and climate forecasting will be even more compelling.

Until recently, forecasters could barely predict space weather in the limited vicinity of Earth. Inter-planetary forecasting was out of the question. This began to change in 2006 with the launch of thetwin STEREO probes followed almost four years later by the Solar Dynamics Observatory. Thesethree spacecraft now surround the sun, monitoring active regions, flares, and coronal mass ejectionsaround the full circumference of the star. No matter which way a solar storm travels, the STEREO-SDO fleet can track it. Missions like SDO and Kepler are giving us a better view of sun-like stars andtheir inner workings to understand their cyclic behavior.

Ultimately, expanding the reach of space weather & climate forecasts throughout the solar systemwill require advances in theory, remote sensing, and computing power. Just recently the CambridgeUniversity Press has published a series of three volumes entitled the Heliophysics Lecture Series thatdeal with this subject matter while the facility called the Community Coordinated Modeling Center(CCMC) are laying the groundwork for the accurate interplanetary forecasts using physics-basedmodels. In this talk I will summarize the observational assests and other resources we have and thechallenges we have to face to move this interdisciplinary field forward.

E-mail: [email protected]

60 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Dynamo Models of Grand Minima

A. R. Choudhuri

Department of Physics, Indian Institute of Science, India

Abstract. The irregularities of solar cycle arise from two main sources - fluctuations in the Babcock-Leighton process for the generation of the poloidal field and fluctuations in meridional circulation. Theeffect of fluctuations in the Babcock-Leighton process is what one would naively expect - less poloidalfield generation at the end of a cycle would make the next cycle weaker. The effect of fluctuations inmeridional circulation in a flux transport dynamo model is more subtle. Weaker meridional circulationmakes the cycle period longer and, only if the dynamo has sufficiently high diffusivity, then the strengthof the cycle becomes weaker - providing an explanation for the Waldmeier effect. Several independentarguments now show that the diffusivity of the dynamo should be high. We address the questionwhether the combined effects of low poloidal field generation and weak meridional circulation canpush the dynamo into a grand minimum like the Maunder minimum. Since the Babcock-Leightonprocess would not operate when there are no active regions, an important question is how the dynamocomes out of the grand minimum. Limited data available for the Maunder minimum suggest thatit started somewhat abruptly and ended more gradually, while the magnetic field in the solar windcontinued the 11-year oscillation at a somewhat suppressed level. We shall discuss how flux transportdynamo models address these issues.

E-mail: [email protected]

61 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

A Simple Dynamo Model for Solar Grand Minima and GeomagneticReversals

D. Sokoloff, G. Sobko, V. Trukhin, V. Zadkov

Department of Physics, Moscow State University, Russia

Abstract. We suggest a simple dynamical system which mimics a nonlinear dynamo which is ableto provide (in specific domains of its parametric space) the temporal evolution of solar magneticactivity cycles as well as evolution of geomagnetic field including its polarity reversals. A qualitativeexplanation for the physical nature of both phenomena is presented and discussed.

E-mail: [email protected]

62 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Is Meridional Circulation Important in Modeling the Irregular SolarCycle?

B. B. Karak, A. R. Choudhuri

Department of Physics, Indian Institute of Science, India

Abstract. The sunspot number varies roughly periodically with time. However the individual cycledurations and amplitudes are found to vary in an irregular manner. It is observed that the stronger cy-cles are having shorter rise time and vice versa. This leads to an important effect known as Waldmeiereffect. Another important feature of the solar cycle irregularity are the grand minima during whichthe activity level is strongly reduced. We explore whether these irregularities can be studied with thehelp of the flux transport dynamo model of the solar cycle. We show that with a suitable stochasticfluctuations in the meridional circulation, we are able to reproduce many irregular features of solarcycle including the Waldmeier effect and grand minimum. However, we are not able to reproducethese results in a low-diffusivity model. Next we introduce a quenching on the meridional circulationdue to the dynamo-generated magnetic fields in the flux transport dynamo model and we show thatthe low-diffusivity model fails to produce stable solar-like solution with this quenching.

E-mail: bidya [email protected]

63 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Grand Minima of Solar Activity on Long-Term Scale

I. G. Usoskin1, S. K. Solanki2

1Sodankyla Geophysical Observatory (Oulu unit), University of Oulu, Finland2Max Planck Institute for Solar System Research, Germany

Abstract. Using a reconstruction of solar activity from cosmogenic isotope data in natural terrestrialarchives, we analyze the statistics of the occurrence of grand minima and maxima over the Holocene,i.e. the past 11 millennia. We present a list of reconstructed grand minima and maxima of solaractivity as well as the statistics of both the length of individual events as well as the waiting timebetween them. We show that the occurrence of grand minima/maxima is not driven by long-termcyclic variability, but is a stochastic/chaotic process. Two different types of grand minima are observed:short (30–90 years) minima of Maunder type and long (> 100 years) minima of Sporer type, implyingthat a deterministic behaviour of the dynamo during a grand minimum defines its length. Theseresults set important observational constraints on long-term solar and stellar dynamo models.

E-mail: [email protected]

64 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Does solar activity affect climate?

B. Mendoza Ortega

Instituto de Geofısica, Universidad Nacional Autonoma de Mexico, Mexico

Abstract. The Sun expels several products of its activity to the interplanetary medium, namelyelectromagnetic radiation, energetic particles, and solar wind and transient ejecta with a frozen-in magnetic field. The bodies embedded in the heliosphere react to the impact of solar activityaccording to their characteristics, i.e. whether or not they have intrinsic magnetic fields, ionosphereor neutral atmosphere. In particular the Earth responds to solar variability through geomagneticactivity, variations of the high atmosphere, and possibly, changes of weather, climate and biota. Sincemany years ago, the effect of solar variability on climate has been the subject of controversy. Severalattempts have been made to estimate the impact of solar variability on climate through the study ofsolar or solar-associated phenomena. Here we discuss the main mechanism currently proposed. Alsowe shall have a glimpse of the effects of a possible grand minimum occurring in the coming years.

E-mail: [email protected]

65 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Effects of Solar Variability on Planetary Plasma Environments andHabitability

C. Bertucci


Abstract. Intrinsic and induced planetary magnetospheres are the result of the transfer of energy andlinear momentum between the Solar Wind and, respectively, the magnetic fields and the atmospheresof solar system bodies. This transfer seems to be, however, more critical to the atmospheric evolutionof unmagnetized objects such as Mars and Venus, as locally ionized planetary particles are acceleratedby solar-wind induced electric fields, leading to atmospheric escape.The nature of the obstacle to thesolar wind being different, intrinsic and induced magnetospheres respond differently to solar cyclechanges in solar photon flux and solar wind properties. In this presentation, we discuss the influenceof solar variability on planetary magnetospheres and its implications for atmospheric evolution basedon in remote, and in situ spacecraft measurements, as well as numerical simulations. In particular,we will discuss the case of unmagnetized objects where nonthermal escape process might have playeda role in their habitability conditions.

E-mail: [email protected]

66 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

EV-Lac as a Potential Host for Habitable Planets

X. C. Abrevaya1, E. Corton2, P. J. D. Mauas1

1IAFE, Argentina2QB-FCEyN-UBA, Argentina

Abstract. At present, dwarf M stars are being considered as potential hosts for habitable planets.However, an important fraction of these stars are flare stars, which among other things emit largeamounts of UV radiation during flares, and it is unknown how this radiation can affect life, sincebiological systems are particularly vulnerable to UV. In this work we evaluate a well known dMe star,EV Lacertae (GJ 873) as a potential site for the emergence and evolution of life, focusing on the effectsof the UV emission associated with flare activity. Since UV-C (λ < 290 nm) is particularly harmful forliving organisms, we studied the effect of UV-C radiation on halophile archaea cultures. The halophilearchaea or haloarchaea are extremophile microorganisms, which inhabit in hypersaline environmentsand show several mechanisms to cope with UV radiation since they are naturally exposed to intensesolar UV radiation on Earth. To select the irradiance to be tested we considered a moderate flare ofthis star. We obtained the mean value for the UV-C irradiance integrating the IAU spectrum in theimpulsive phase, and considering a hypothetical planet in the center of the liquid water habitabilityzone. To select the irradiation times we took the most frequent duration of flares on this star whichis from 10 to 30 minutes. Our results show that even after considerable UV damage, the haloarchaeacells survive at the tested doses, showing that this kind of life could survive in a relatively hostile UVenvironment.

E-mail: [email protected]

67 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Geomagnetic Storms and Solar Activity since 1806

V. Bothmer, E. Bosman

University of Gottingen Institute for Astrophysics, Germany

Abstract. In 1806 Alexander v. Humboldt measured fluctuations of the Earth’s magnetic fieldsimultaneously with the appearances of aurora in the sky above Berlin, published in ”Annalen derPhysik” in 1808. Carl Friedrich von Gauss later on recorded aurora at the Goettingen sky in theyears 1836–1841. Today it is known from satellite observations that major geomagnetic storms arecaused by fast coronal mass ejections from the Sun. However it is still a matter of debate what thesolar requirements are to cause such geomagnetic superstorms and what their occurrence rate is withrespect to the solar activity cycle. This presentation presents the results of a statistical survey onthe relationship of geomagnetic activity and geomagnetic superstorms to the sunspot cycle based onextrapolations of Ap, Kp back to 1806, taking into account results derived from space observationssince 1964. It will be shown that superstorms in history appeared even during very moderate phasesof solar activity and that the last solar minimum is comparable to conditions around 1903.

E-mail: [email protected]

68 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Historical Records of Solar Grand Minima: a Review

J. Vaquero

Universidad de Extremadura, Spain

Abstract. Knowing solar activity during the past centuries is of great interest for many purposes.Historical documents can help us to know about the behaviour of the Sun during the last centuries.The observation of aurorae and naked-eye sunspots provides us with continuous information throughthe last few centuries that can be used to improve our knowledge of the long-term solar activityincluding solar ”Grand Minima”. We have more or less detailed information on only one Grandminimum (the Maunder minimum in the second half of 17th century), which serves as an archetypefor Grand minima in general. Telescopic sunspot records and measurements of solar diameter duringMaunder minimum are available. In this contribution, I review some recent progress on these issues.

E-mail: [email protected]

69 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Variations of Solar and Cosmic Ray Cycles at the Maunder Minimum

H. Miyahara1, Y. Yokoyama1, Y. T. Yamaguchi1, H. Matsuzaki1, K. Horiuchi2, H. Motoyama3, F.Tokanai4, H. Kato4

1The Univ. of Tokyo, Japan2Hirosaki Univ., Japan3NIPR, Japan4Yamagata Univ., Japan

Abstract. We present the variations of solar and cosmic-ray decadal/bi-decadal cycles at the MaunderMinimum, observed using the cosmogenic nuclides in tree rings and ice cores. Annually resolved recordsof beryllium-10 content from ice cores have indicated the abrupt increase of cosmic rays at the everyother minima of solar cycles with 14 years. It has resulted in the amplification of solar Hale magneticcycles at the Maunder Minimum. The anomalous cosmic-ray enhancement events with ∼E1 yeardurations were observed at the phases when solar dipole magnetic field was negative. It suggeststhe changed structure of heliospheric magnetic field at the sunspot absence, which can intensify themanifestation of drift effect on cosmic ray modulation. In this paper we also discuss the transitions ofsolar cycles at the onset of the Maunder Minimum based on the precisely measured carbon-14 contentin tree rings.

E-mail: [email protected]

70 3-7 October 2011 – Mendoza, Argentina

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Poster Contributions

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Solar Grand Minima and On-Off Intermittent Dynamo

A. C. L. Chian1,2, A. Brandenburg3, M. R. E. Proctor4, E. L. Rempel5

1Paris Observatory-Meudon, France2INPE, Brazil3NORDITA, Sweden4U. Cambridge, UK5ITA, Brazil

Abstract. Solar cycle is a manifestation of solar dynamo where the distribution of sunspots in spaceand time display large-scale spatial coherence and long-term temporal correlation, as seen in thebutterfly diagram. The recurrent 11-yr solar cycles and grand minima such as the Maunder Minimumsuggest a description of solar cycles as an on-off intermittency (He & Chian, PRL 91, 034102, 2003;Rempel & Chian, PRL 98, 014101, 2007; Chian et al., PRL 104, 254102, 2010) resulting from thechaotic nature of solar dynamo.

The transition to an intermittent mean-field dynamo is studied using 3D numerical simulations ofcompressible magnetohydrodynamic turbulence driven by a helical forcing, by varying the magneticdiffusivity. Prior to the onset of dynamo action, a transient mean field with low magnetic energy isobserved. After the transition to a sustained dynamo, the system is shown to evolve to an on-offintermittency whereby the magnetic field randomly alternates between periods of bursty and laminarfluctuations, typical of solar cycles (Rempel, Proctor & Chian, MNRAS 400, 509, 2009).

We report the detection of Lagrangian coherent structures (LCS) which act as transport barriersin a turbulent dynamo. A travelling-wave regime and a wave turbulence regime are identified asthe magnetic diffusivity is varied. The sharp contrast between the dynamics of LCS in these twodynamo regimes permits a unique analysis of the impact of the magnetic field on the velocity field,which provides an in-depth view of the origin of intermittency in solar cycles (Rempel, Chian &Brandenburg, ApJL 735, L9, 2011).

E-mail: [email protected]

72 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Plasma Flow vs. Magnetic Feature-Tracking Speeds in the Sun

G. Guerrero1, M. Rheinhardt2, A. Brandenburg1, M. Dikpati3

1NORDITA, Sweden2Department of Astronomy, Stockholm University, Sweden3High Altitude Observatory, National Center for Atmospheric Research, USA

Abstract. We simulate the magnetic feature tracking (MFT) speed using advective-diffusive transportmodels in both one and two dimensions. By depositing magnetic bipolar regions at different latitudesat the Sun’s surface and following their evolution for a prescribed meridional circulation and magneticdiffusivity profiles, we derive the MFT speed as a function of latitude. We find that in a one dimensionalsurface-transport model the simulated MFT speed at the surface is always the same as the meridionalflow-speed used as input to the model, but is different in a two-dimensional transport model in themeridional (r-theta) plane. The difference depends on the value of the magnetic diffusivity and on theradial gradient of the latitudinal velocity. We have confirmed our results with two different codes inspherical and Cartesian coordinates.

E-mail: [email protected]

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The Butterfly Diagram Structure in the Minimal Activity Phases

M. Ternullo, P. Romano

INAF/Catania, Italy

Abstract. In any solar cycle, the spot formation process is highly discontinuous. It can be properlydescribed as a sequence of pulses of activity, each one enduring not longer than a couple of months andinvolving photospheric regions tightly limited in latitude. If the amount of magnetic flux conveyedby spotgroups is accounted for in a Butterfly Diagram, it appears that most magnetic flux eruptedin a cycle is concentrated in small portions (’knots’) of the Diagram. The popular belief that spotsare distributed about a line (the spot ’mean latitude’) crossing any butterfly wing and continuouslyapproaching the equator is disproved from our results. Knots appear, on the contrary, in a seeminglyrandom manner, each one at a latitude either lower or even higher than previous ones, even thoughrespecting the overall tendency to approach equator. The suggestion arises that the spot cycle consistsin two - or more - activity waves per cycle in any solar hemisphere; this two-wave structure appearsclearer both at the beginning and ending phases of the cycle.

E-mail: [email protected]

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Creating a Database and Analysis of Sunspots at the Solar Observa-tory of Ica National University in Peru

L. Martınez Meneses1, M. Ishitsuka2, J. Ishitsuka2, H. Trigoso2

1Universidad Nacional San Luis Gonzaga de Ica, Peru2Geophysical Institute of Peru

Abstract. We have created a database and analysed sunspots recorded at the Solar Observatory of theIca National University, taking as reference the International Relative Sunspot Number. Equipmentsand scientific advice is provided by the Astronomy Division of the Geophysical Institute of Peru. Thisprocess will allow us to find a methodology in order to systematize the analysis of the evolution ofactive regions (sunspots). We are also looking for a technique that allows consistency of the data.The quality of data is very important in order to calculate the position, areas, rotation speed, andother properties of the Active Regions. The data of sunspots were taken from 2003 until 2006, theserecords of sunspots were obtained by using the projection method, by different observers.

E-mail: [email protected]

75 3-7 October 2011 – Mendoza, Argentina

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Study of Ground Cosmic Ray Periodicities during Solar MinimumUsing the Multidirectional Muon Detector at the Southern SpaceObservatory

A. Dal Lago1, L. Ramos Vieira1, N. J. Schuch2, N. R. Rigozo2

1National Institute for Space Research, INPE, Brazil2South Regional Space Research Center, CRS/INPE, Brazil

Abstract. This work presents a study of the periodicities observed in ground cosmic rays datafrom the Multidirectional Muon Detector at the Southern Space Observatory - SSO, Brazil, (29.4◦S,53.8◦W, 480 m above sea level), during the minimum phase of the solar cycle. The period of analysiswas the years of 2007, 2008, 2009 and 2010. Wavelet technique was used to investigate the presenceof the periodicities throughout the time. As expected, the 27-day period is observed in some parts ofthe time series, as well as the 13.5-day period, indicating the influence of the solar rotation and itsharmonics. Other longer periods are also found in this study.

E-mail: [email protected]

76 3-7 October 2011 – Mendoza, Argentina

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Long-term Variation of Solar Wind Parameters and their Geoeffec-tiveness

V. C. Dwivedi, D. P. Tiwari, S. P. Agrawal

Physics Department A.P.S. University, India

Abstract. The interplanetary parameters used for the study of solar-terrestrial relationships aresolar wind speed (V), the total interplanetary magnetic field (B) and the southward component ofIMF (Bz). For our study, we have used the daily values of the interplanetary indices (V, B and VB),as well as the daily values of the geomagnetic disturbance index Ap, for the years 1965 to 2010. Thelong-term averages have been calculated for the days when simultaneous data is available for all thefour parameters (V, B, Bz and Ap). These include their averages on the basis of the phases of thesolar activity cycle. The statistical relationship between them has been investigated on these long-termaverages, as well as on the day-to-day basis. The results so obtained can be summarized as (i) V vsAp has always low values of correlation coefficient (r), (ii) on the contrary, B vs Ap has high values of”r”, (iii) the product of V and B vs Ap always yields much better correlations than for V or B alone,either on an average basis, or on a day-to-day basis, and (iv) even though, the long-term variationsof V are not very significant, the variations of B follow solar activity cycle and has a continuouslyincreasing trend during the solar cycles 20 and 21. The statistical results obtained here signify thatthe VB is more significantly effective in producing large-scale geomagnetic disturbances.

E-mail: [email protected]

77 3-7 October 2011 – Mendoza, Argentina

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Observations of Coronal Holes During Two Solar Minima

H. Gutierrez, L. Taliashvili

CINESPA, UCR, Costa Rica

Abstract. The study of short- and long-term evolution of equatorial and polar coronal holes asisolated events and also, associated with other activities, such as solar prominences and active regionsis made during the selected periods of two solar minima of the years 1996 and 2009; based on theanalyses of SOHO/EIT and STEREO multispectral data sets and Carrington Rotation maps. Wediscuss about characteristics of the evolution of coronal holes accompanied or not by transient coronalholes associated with the origin or/and post evolution of Coronal Mass Ejections.

E-mail: [email protected]

78 3-7 October 2011 – Mendoza, Argentina

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Coronal Mass Ejection Deflection in the Corona during the Last TwoSolar Minima

F. M. Lopez1, H. Cremades2, L. Balmaceda3

1UNSJ, Argentina2UTN-FRM/CONICET, Argentina3ICATE-CONICET-UNSJ, Argentina

Abstract. The Whole Sun Month (WSM) and the Whole Heliosphere Interval (WHI) solar obser-vation and modeling campaigns took place during two different solar minima, each of them coveringa full solar rotation. The wealth of available data for these two time periods allows the study ofspecific features and events during two distinct solar minima. In the framework of the IAU WorkingGroup on Comparative Solar Minima, we investigate the deflection of Coronal Mass Ejections (CMEs)with respect to the location of their solar source regions. The hypothesis that the global magneticfield configuration affects the propagation direction of CMEs can be subjected to examination, giventhat during the WSM minimum the global magnetic field was essentially dipolar, with a solar coronamanifesting only equatorial streamers and large polar coronal holes; while the last solar minimum didnot reach that basic configuration, rather showing at least three streamers at a time and several lowlatitude coronal holes. Different patterns of CME deflection are observed, likely due to these intrinsicdifferences between the two minima.

E-mail: [email protected]

79 3-7 October 2011 – Mendoza, Argentina

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A Cellular Automaton Model for Coronal Heating

M. Lopez Fuentes1, J. A. Klimchuk2


Abstract. We present a simple coronal heating model based on a cellular automaton approach.Following Parker’s suggestion (1988, ApJ, 330, 474), we consider the coronal structure made of ele-mental magnetic strands that accumulate magnetic stress due to the photospheric displacements oftheir footpoints. Magnetic energy is eventually released in small scale reconnection events. The modelconsists of a 2D grid in which strand footpoints travel with random displacements simulating con-vective motions. Each time two strands interact, a critical condition is tested (as in self-organizedcritical models), and if the condition is fulfilled, strands reconnect and energy is released. We modelthe plasma response to the heating events and obtain synthetic observations from the known responseof different instruments. We compare the output of the model with real observations from SDO/AIAand Hinode/XRT and discuss the implications of our results for coronal heating.

E-mail: [email protected]

80 3-7 October 2011 – Mendoza, Argentina

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Magneto-seismology of Solar Atmospheric Loops in the Solar Mini-mum

M. Luna Cardozo1, G. Verth2, R. Erdelyi3

1IAFE, Argentina2Northumbria University, UK3University of Sheffield, UK

Abstract. There is increasingly strong observational evidence that slow magnetoacoustic modesarise in the solar atmosphere. Solar magneto-seismology is a novel tool to derive otherwise directlyun-measurable properties of the solar atmosphere when magnetohydrodynamic (MHD) wave theoryis compared to wave observations. Here, MHD wave theory is further developed illustrating howinformation about the magnetic and density structure along coronal loops can be determined bymeasuring the frequency of the slow MHD oscillation. The application to observations in the solarminimum of slow magnetoacoustic waves in solar atmospheric loops is considered.

E-mail: [email protected]

81 3-7 October 2011 – Mendoza, Argentina

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High-Speed Streams in the Solar Wind during the Last Solar Mini-mum

G. Maris1, O. Maris2, C. Oprea1, M. Mierla1

1Institute of Geodynamics of the Romanian Academy, Romania2Institute for Space Sciences, Romania

Abstract. The paper presents a detailed analysis of the fast solar wind streams during the lastprolonged minimum. Defining a minimum phase as the period with the smoothed monthly relativesunspot number having value less than 20, we considered for this analysis the interval February 2006– September 2010. The High-Speed Streams (HSSs) in the solar wind were determined by their mainparameters: duration, maximum velocity, velocity gradient. The HSS importance parameter was alsocalculated for each stream. The main features of the fast streams and their solar sources were markedout. A comparative analysis of the HSS dynamics during the last solar minimum with the previoussolar minimum (1996–1997) concludes the paper.

E-mail: [email protected]

82 3-7 October 2011 – Mendoza, Argentina

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Geomagnetic Effects on Cosmic Rays Propagation under DifferentConditions

J. J. Masıas Meza1, X. Bertou1, S. Dasso2,3

1Centro Atomico Bariloche (CNEA/CONICET), U.N. de Cuyo, Argentina2Instituto de Astronomıa y Fısica del Espacio (IAFE, UBA-CONICET)3Departamento de Fısica (FCEN-UBA), Argentina

Abstract. During the last solar minimum, the galactic cosmic rays flux presented the highest levelobserved since the birth of the space age. In order to quantify the low fluxes of cosmic particles withenergies larger than several GeVs, it is necessary to observe them using terrestrial observatories atground level with a relatively large collecting surface. To properly interpret any ground observation,it is necessary to consider the effects of the geomagnetic field on the trajectory of these electricallycharged particles. In this work, using numerical simulations, we explore the main effects of thegeomagnetic field on the propagation of particles with energies inside the 1GeV–1TeV range, on theirway to the surface of the Earth. In particular, we study the sites of the giant Pierre Auger cosmic rayobservatory of Malargue (Mendoza, Argentina) and of the Rome Neutron Monitor, sites with similarrigidity cut off. We determine the asymmetry in the angular distribution (zenith and azimuth) ofenergy cuts and the yearly drift of this energy cut in the last 20 years. We also analyse simulationsfor different conditions of space current in the magnetosphere (i.e., different levels of geomagneticstorm). We find that excitations of the magnetospheric currents (e.g., Van Allen’s ring currents) playan important role in determining the energy spectrum of primary cosmic particles arriving at theatmosphere of the Earth. The latter is crucial when interpreting ground level observations, and willallow the comparison of the Pierre Auger Observatory data with data from Neutron Monitors.

E-mail: [email protected]

83 3-7 October 2011 – Mendoza, Argentina

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Forbush Decreases not Related to Transient Solar Events

G. Munoz Martınez, J. F. Valdes Galicia

1IBERO, Mexico2IGEOF/UNAM, Mexico

Abstract. Forbush Decreases (FD) are commonly related to solar eruptive events such as Flares,CMEs and their effects on the interplanetary space, specially ICMEs. In most of the cases oneor more of these transient solar events are involved, more than one is present, as shock, magneticclouds, etc and it is difficult to distinguish which of them has an specific counterpart. Even whenthe correlation to these events is clear in most of the cases, the physical mechanisms originating FDis not clear. In this work we analyzed a number of FD where apparently no eruptive event in theSun or when the interplanetary transient event was found to be temporally related. We identified themain characteristics of interplanetary parameters that may be associated to a specific mechanism notrelated to transient solar events.

E-mail: [email protected]

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The 3D Solar Corona Cycle 24 Rising Phase from SDO/AIA Tomog-raphy

F. Nuevo1, A. M. Vasquez1, R. A. Frazin2, Z. Huang2,W. B. Manchester IV2

1Instituto de Astronomıa y Fısica del Espacio (CONICET-UBA) and FCEN (UBA), Argentina2Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, USA

Abstract. We have recently extended the Differential Emission Measure Tomography (DEMT) tech-nique to be applied to the six iron bands of the Atmospheric Imaging Assembly (AIA) instrumentaboard the Solar Dynamics Observatory (SDO). The AIA based DEMT products are the 3D recon-struction of the coronal emissivity in the instrument’s six coronal bands, and the 3D distribution ofthe local differential emission measure (LDEM), in the height range 1.00 to 1.25 Rsun. Based on thereconstructed LDEM, in this work we show 3D maps of the electron density and temperature of theinner solar corona during the rising phase of solar cycle 24. We discuss the 3D distribution of ourresults in the context of open/closed magnetic regions, as derived from a global potential field model ofthe same period. We also discuss the new information gained with SDO/AIA respect to our previoustomographic results based on the three coronal bands of STEREO/EUVI.

E-mail: [email protected]

85 3-7 October 2011 – Mendoza, Argentina

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Earth-directed Coronal Mass Ejections and their Geoeffectivenessduring the 2007–2010 Interval

C. Oprea, M. Mierla, G. Maris

Institute of Geodynamics of the Romanian Academy, Romania

Abstract. In this study we analyse the CMEs directed towards the Earth during the interval 2007–2010, using the data acquired by STEREO mission and those provided by SOHO, ACE and geomag-netic stations. A study of solar sources and CMEs kinematics will be done. This will be correlatedwith CMEs interplanetary manifestations and their geomagnetic effects, along with the energy trans-fer flux into magnetosphere (the Akasofu coupling function). The chosen interval that is practicallycoincident with the last solar minimum, offered us a good opportunity to link and analyse the chainof phenomena from the Sun to the terrestrial magnetosphere in an attempt to better understand thesolar and heliospheric processes that can cause major geomagnetic storms.

E-mail: const [email protected]

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Evolution of a Very Complex Active Region during the Decay Phaseof Cycle 23

M. Poisson1, M. Lopez Fuentes1, C. H. Mandrini1, E. Pariat2, P. Demoulin2

1IAFE/CONICET-UBA, Argentina2LESIA/Observatoire de Paris - Meudon, France

Abstract. It is generally observed that most magnetically complex active regions (AR) tend toappear on the late phases of solar cycles. Here, we study a particular case of extreme complexity:AR NOAA 10314, that has been observed from March 13 to 19, 2003, during the decay of Cycle 23.AR 10314 was the source of several energetic events, among them two major (X class) flares, along afew days. We followed the evolution of this AR since the very first stages of its emergence. From thephotospheric evolution of the magnetic polarities observed with SOHO/MDI magnetograms we inferthe morphology of the flux tube that originates the AR. Using a sophisticated computation techniquethat combines Local Correlation Tracking with magnetic induction constrains we compute the rateof magnetic helicity injection at the photosphere during the observed evoution. From our results weconclude that the AR was produced by the emergence of a severely deformed magnetic flux tubehaving a dominantly positive magnetic helicity.

E-mail: [email protected]

87 3-7 October 2011 – Mendoza, Argentina

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Cosmic Ray Particles Behavior during the Last Solar Minimum

M. Rockenbach Da Silva1, A. Dal Lago2, W. D. Gonzalez2, K. Munakata3, C. Kato3, T. Kuwabara4,J. Bieber4, N. Schuch5, M. L. Duldig6, J. E. Humble7, H. K. Al Jassar8, M. M. Sharma8, I. Sabbah9

1Instituto de Pesquisa e Desenvolvimento, Universidade do Vale do Paraıba, Brazil2National Institute for Space Research (INPE-MCT), Brazil3Department of Physics, Shinshu University, Japan4Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, USA5Southern Regional Space Research Center (CRS/CCR/INPE-MCT), Brazil6Australian Antarctic Division, Australia7School of Mathematics and Physics, University of Tasmania, Australia8Physics Department, Faculty of Science, Kuwait University, Kuwait9Department of Natural Sciences, Collage of Health Sciences, the Public Authority of Applied Edu-cation and Training, Kuwait

Abstract. The work presents the Heliosphere characterization during the minimum solar activity. Itis possible to identify phenomena caused by the Corrotating Interaction Regions (CIRs), during thissolar activity phase. CIRs can be visualized in satellite data for each 27 days, approximately, andit is frequently accompanied by the Earth crossing through the Heliospheric Current Sheath (HCS).This crossing occurs in a period of time lower than a day, and it is possible to study the behavior ofcosmic rays particles in two different regions with opposite magnetic field polarities. The last solarminimum was special because their long duration and it was the first that the Global Muon DetectorNetwork - GMDN operated in its full capacity. This cosmic ray detectors network is composed bymuon scintillators installed in Nagoya, Japan; Hobart, Australia, Sao Martinho da Serra, Brazil,and Kuwait City, Kuwait. Analyzing the GMDN data together with data from SOHO and/or ACEsatellites it is possible to study the behavior of the cosmic ray particles and present a Heliospherecharacterization during the minimum solar activity, giving a better understanding of the cosmic rayparticles modulation.

E-mail: [email protected]

88 3-7 October 2011 – Mendoza, Argentina

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Radio Signatures Associated with the Origin of LASCO/STEREOCMEs

C. Salas Matamoros, L. Taliashvili


Abstract. We present the comparative study of the origin of LASCO/STEREO Halo and narrowCoronal Mass Ejections (CMEs) associated to the same active region and also, CMEs associated to thedistinct near-by active regions with consecutive Hα and X-ray flares accompanied by different type ofradio bursts and the disappearance of filaments around the recent solar minimum, during descendingand enhancing solar activity phases of the years 2006 and 2010. We discuss about the radio signaturesassociated with the origin of the studied CMEs.

E-mail: [email protected]

89 3-7 October 2011 – Mendoza, Argentina

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Very Intense Geomagnetic Storms: Solar Sources, Characteristicsand Cycle Distribution

N. Szajko1, G. Cristiani1, C. H. Mandrini1, A. Dal Lago2

1Instituto de Astronomıa y Fısica del Espacio, Argentina2Instituto Nacional de Pesquisas Espaciais, Brazil

Abstract. Using the Dst time series we have identified all the very intense geomagnetic storms thatoccurred during Solar Cycles 21, 22 and 23. A value of Dstmin <-200 nT has been set as thresholdfor this identification. We analize the geomagnetic storm distribution over each solar cycle, finding inCycles 21 and 23 the largest storm concentration during the declining phase. In Cycle 22, which showstwo separated peaks, the larger storm occurrence is coincident with the period beetwen these peaks.For Cycle 23 the series of storms is compared to solar and interplanetary observations from LASCO andEIT aboard SOHO and SWEPAM and MAG aboard ACE. By timing the solar, interplanetary, andEarth events we have been able to identify the solar and interplanetary sources of each geomagneticstorm.

E-mail: [email protected]

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A Solar Station in Ica: A Research Center to improve Education atthe University and Schools

R. Terrazas Ramos1, M. Ishitsuka2, J. Ishitsuka2, H. Trigoso2

1Universidad Nacional San Luis Gonzaga de Ica, Peru2Instituto Geofısico del Peru, Peru

Abstract.The Universidad Nacional San Luis Gonzaga de Ica has built a Solar Observatory in co-operation with Geophysical Institute of Peru and National Astronomical Observatory of Japan. Atthe Solar Station, the following equipments are installed: a Digital Monochromatic heliograph, a Dig-ital Solar Spectrograph, a Takahashi Refractor Telescope of 15 cm of aperture and the FMT (FlareMonitor Telescope) from Hida Observatory of Kyoto University. These equipments contribute to thedevelopment of Astronomical Science in Peru and also to worldwide sciences. The development of thebasic sciences will be guaranteed when the university students, teachers and researchers work together.The Solar Station will be useful for the study at different levels of university education and also forthe general public and schools. The Solar Station will be a good mean to spread science in the regionthrough public outreach.

E-mail: [email protected]

91 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Solar Radius and Limb Brightening Variability in the SubmillimetricRange

L. A. Balmaceda1, A. Valio2, C. L. Selhorst3

1ICATE-CONICET-UNSJ, Argentina2Centro de Radio Astronomia e Astrofısica Mackenzie (CRAAM), Brazil3Universidade do Vale do Paraıba - UNIVAP, Brazil

Abstract. We study the variation of the solar radius and the limb brightening at 212 and 405 GHz,during the recent extended minimum of solar cycle XXIII. For this purpose, daily maps obtainedwith the Solar Submillimeter-wave Telescope (SST) operating at El Leoncito, Argentina, since 1999are analyzed. In order to interpret the results, the estimated parameters are contrasted with a semi-empirical model of the solar atmosphere. A comparison with different indices of solar activity, suchas sunspot number and solar irradiance, is also carried out.

E-mail: [email protected]

92 3-7 October 2011 – Mendoza, Argentina

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A Statistical Analysis of the Hα-Ca II K Relation for Solar-TypeStars of Different Activity Levels

A. P. Buccino, M. C. Vieytes, P. J. D. Mauas

IAFE, Argentina

Abstract. The usual indicator of chromospheric activity of dF to dK stars is the well known MountWilson S index, essentially the ratio of the flux in the core of the Ca II H and K lines to the continuumnearby. Another common activity proxy is the Hα-line. For a long time, it has been claimed thatboth proxies were tightly correlated.

However, based on our large spectra database obtained at CASLEO Argentinian Observatory, in 2007our group found that the correlation between Ca II and Hα is mainly related to a colour componentand is not the product of an activity phenomena (Cincunegui et al. A&A 469, 309). We found thatwhile some stars exhibit correlations between Hα and the Ca II lines, the slopes change from star tostar, including cases where no correlation was found. Recently, Meunier and Delfosse (2009, A&A,501, 1103) studied the contribution of plages and filaments in the Hα–Ca II relation in the Sun fordifferent time scales, in an attempt to explain our previous results.

To date, our observing program is 12 years old, we have a large spectra database of 150 stars from dF6to dM5. These spectra are calibrated in flux and allow us to simultaneously study different spectralfeatures, from the Ca II lines to Hα. To discern if this flux-flux relation depends on the level of activityof the star and if it is associated to the distribution of active regions in the stellar atmosphere, in thiswork we analyze the relation between Hα–Ca II K fluxes individually for a set of a several solar-typestars of different level of activity. In particular, for variable stars, we analyze the Hα–Ca II relationduring the minimum and maximum of their chromospheric active regime.

E-mail: [email protected]

93 3-7 October 2011 – Mendoza, Argentina

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Determination of the Effective Temperature from Hα Spectral LineAnalysis of Solar-Type Stars

D. Cornejo Espinoza1, I. Ramırez2, P. Barklem3, W. Guevara Day1

1Departamento de Astrofısica, Agencia Espacial del Peru- CONIDA, Peru2Carnegie Observatories, USA3Uppsala Astronomical Observatory, Sweden

Abstract. The flux level in the wings of the absorption lines from the Balmer series in cool dwarf starslike the sun is a good indicator of the star’s effective temperature (Teff ). We present a spectroscopicstudy of 68 solar-type stars to compute their effective temperatures by the Balmer line wing fittingprocedure and compare them with the values obtained using other commonly employed methods. Weperform a spectroscopic study use the wings of the Hα spectral line (6563 A) and a very fine gridof theoretical models calculated with the best atomic data and most recent quantum theory. Ourspectroscopic data are of very high quality and have been carefully normalized to recover the propershape of the Hα line profile. We obtain Teff values with internal errors of about 20 K.

E-mail: [email protected], [email protected]

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Calibrating the Sun-as-a-Star: Using Hinode XRT to Measure StellarCoronae

S. H. Saar, P. Testa


Abstract. Despite decades of X-ray observations of both solar and stellar coronae with variousinstruments, the precise position of solar X-ray emission levels in a broader astrophysical context issurprisingly uncertain. This is largely due to cross-calibration problems and the difficulty in observingthe same targets with both solar and stellar instruments. Here we report on a new attempt at directcross-calibration between solar and stellar missions: observations by Hinode XRT of a young, X-rayactive F star HD 199143. This star has been previously studied by ROSAT and Chandra, and iseclipsed by the Sun every January. We observed the star in the Al-poly filter for a total of ∼12 hourson ingress and egress. After careful data processing, we searched for a small excess along the star’sapparent path. We discuss the tentatively successful results in the context of the most up-to-datecalibrations of Hinode, Chandra and ROSAT count rates for this star, as well as further observationaland analysis plans.

E-mail: [email protected]

95 3-7 October 2011 – Mendoza, Argentina

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Potential Energy Stored by Planets and Grand Minima Events

R. G. Cionco

UTN-FRSN, Argentina

Abstract. Recently, Wolff and Patrone (Solar Phys, 2010; 266:227–246), have developed a simple butvery interesting model by which the movement of the Sun around the baricenter of the Solar systemcan creates potential energy that can be released by flows pre-existing inside the Sun (or another stars).Taking into account all the literature, this is the first mechanism showing how planetary movementscan modify internal structure in the Sun that can be related to solar cycle. In this work I calculatethe temporal evolution of potential energy (PE) stored in putative zones of Sun’s interior in whichthe PE is most efficiently stored taking into account detailed baricentric Sun dynamics. I show strongvariations of PE specially related to Grand Minima events (GM) and discuss possible implications ofthis mechanism to solar cycle, specially GM events.

E-mail: [email protected]

96 3-7 October 2011 – Mendoza, Argentina

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A New Imminent Grand Minima?

R. G. Cionco1, R. H. Compagnucci2

1UTN-FRSN, Argentina2DCAO-UBA, Argentina

Abstract. The planetary hypothesis of solar cycle is a former idea by which the planetary gravityacting on the Sun might have a non-negligible effect on the solar magnetic cycle. The advance ofthis hypothesis is based on phenomenological correlations between dynamical parameters of the Sun’smovement around the barycenter of the Solar System and sunspots time series. In addition, severalauthors have proposed, using different methodologies that the first GM of the new millennium iscoming or has already begun. We present new fully three dimensional Nbody simulations of the solarinertial motion (SIM) around the barycentre of the solar system in order to perform a phenomenologicalcomparison between relevant SIM dynamical parameters and the occurrences of the last GM events(i.e., Maunder and Dalton). Our fundamental result is that the Sun acceleration decomposed in aco-orbital reference system shows a very particular behaviour that is common to Maunder minimum,Dalton minimum and the maximum of cycle 22 (around 1990). These dynamical events are unique atthese epochs and never have occurred before at least in the past millennium. We discuss our resultsin terms of a possible ’dynamical characterization’ of GM with relation to Sun dynamics. Thesedynamical similarities support the idea of an imminent important minimum.

E-mail: [email protected]

97 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Long Term Relation between Sunspot Activity and Surface Temper-ature at Different Geographical Regions

M. P. Souza Echer1, E. Echer1, W. D. Gonzalez1, N. R. Rigozo2, D. J. R. Nordemann1

1Instituto Nacional de Pesquisas Espaciais, Brazil2Instituto Nacional de Pesquisas Espaciais, Centro Regional Sul, Brazil

Abstract. The global surface temperature has risen since ∼1900. The anthropogenic activity mayhave contributed partially to this variation of the temperature through enhanced greenhouse gasesemissions. However, the climate system is characterized by cyclical natural patterns, and the roleof external forcing, such as solar activity, can not be underestimated. In this work, we comparethe long term variability of solar activity (as quantified by the sunspot number) with several surfacetemperature series from different geographical regions (global, hemispheric and latitudinal ranges).The interval of analysis is 1880–2005 and the data are analyzed with wavelet multiresolution technique.It has noted that a maximum in solar activity occurred around ∼1970, while temperature series showstill a trend of rise after that. There are differences in the long term temperature trend for northernand southern hemisphere latitudes. These differences and the relation with sunspot activity will bediscussed in this work.

Keywords: Sunspot number; Surface air temperature; Long trend; Sun-Climate; Wavelet

E-mail: [email protected]

98 3-7 October 2011 – Mendoza, Argentina

Page 106: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Parallels among the ”Music Scores” of Solar Cycles, Space Weatherand Earth’s Climate

Z. Kollath1, K. Olah1, L. van Driel-Gesztelyi1,2,3

1Konkoly Observatory, Hungary2MSSL, University College London, UK3Paris Observatory, LESIA, France

Abstract. Solar variability and its effects on the physical variability of our (space) environmentproduce complex signals. In the indicators of solar activity at least four independent cyclic componentscan be identified, all of them with temporal variations in their timescales. Time-frequency distributionsare perfect tools to disclose the ”music scores” in these complex time series. Special features in thetime-frequency distributions, like frequency splitting, or modulations on different timescales provideclues, which can reveal similar trends among different indices like sunspot numbers, interplanetarymagnetic field strength in the Earth’s neighborhood and climate data. Parallels and differences of thedifferent periodic components within the same dataset, like modulations of the harmonics of the lengthof the 11-year solar cycle, provide additional clues for understanding processes like the Waldmeier-effect. Analyzing long-term data with such ”music scores” can bring to light recurrent structureshidden in other data representations. These recurrent ”tunes”, due to their regular nature, can beused for forecasting the cycle. The long-term modulation of solar activity went over a frequencyshift (a glissando) around 1700, most probably in connection with a frequency split in the Gleissbergcycle. This frequency shift event is strongly related to the termination of the Maunder minimum. Weidentify a very similar structure in the ”scores” of recent solar activity, starting around 1950. We askthe question whether or not this frequency shift can be a precursor of the behavior of the recent solarcycle.

E-mail: [email protected]

99 3-7 October 2011 – Mendoza, Argentina

Page 107: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

TTVs Detection in Southern Hemisphere Stars

R. Petrucci1, A. Buccino1, E. Jofre2, M. Schwartz1, P. Mauas1, M. Melita1

1IAFE, Argentina2OAC, Argentina

Abstract. Since the discovery of the first extrasolar planet around a main sequence-star (Mayor &Queloz 1995) more than 500 planetary-mass objects orbiting around stars with different characteristics(spectral type, evolutive stage, etc) have been detected. Until now, the most fruitful detection tech-niques are: i) the Doppler method, based on measurements of stellar radial-velocity periodic variationsdue to the gravitational pull exerted by a near planet; ii) the transit method, where the presence ofplanets manifests through stellar light variations caused by the transit of a planet in front of the star’sdisk. Measurements from the first method lead to determine period, eccentricity and minimun massof the planet. Transit observations provide orbital period and planetary radius.

Combining the parameters obtained from both techniques, it would be possible determine the planetarydensity. However, none of these methods would be sensitive for a planet as small as Earth, particularlyif surveys are ground-based. The TTVs (transit timming variations) are the only method capable ofdetecting Earth-size planets and whose detections can be confirmed latter.

It is well known that the time interval between succesive transits of an unperturbed planet is alwaysthe same. But the presence of another planetary-mass body in the system can produce variationsof the transiting-planet period duration due to their gravitational interaction. These TTVs (transittimming variations) depend on the mass of the additional planet, and in some cases terrestrial-massplanet will produce a measureble effect. Even more exciting, systems in which two planets transit theirstar, the masses and radii of each planet (and therefore their densities) can be determined withoutradial-velocity measurements. The feasibility of detecting additional planets in transiting systemsusing TTVs, depends on the accuracy with which the middle of the transit can be measured and thetime-interval between observations (Holman & Murray 2005).

On the other hand, at present there are many groups around the world using small telescopes lookingfor TTVs in transiting systems (Ford et al. 2011, Fukui et al. 2011, Payne & Ford 2011). Theadvantage of these over big telescopes is that it is possible to do a continuos photometric monitoringof many targets.

Taking into account all of this, we present the first measurements of planetary transits made with theHoracio Ghielmetti Telescope (THG) located at the Complejo Astronomico El Leoncito (CASLEO) inArgentina. This telescope is a 40 cm MEADE, which can be remotely controled. The main purposeof this instrument is the detection of TTVs in transiting systems from the Southern Hemispherethrough great quality observations and high-precision photometry. Even more, in the future we planto incorporate cold stars to our sample in a attempt to find long-term photometric variations whichcan indicate the presence of stellar activity.

E-mail: [email protected]

100 3-7 October 2011 – Mendoza, Argentina

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IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Climate Interaction Mechanism Between Solar Activity and Terres-trial Biota

J. Osorio Rosales, B. Mendoza Ortega

Instituto de Geofısica, UNAM, Mexico

Abstract. The solar activity has been proponed as one of main factors of Earth climate variability,however other kind of biological process has been proposed too. Actually it is accepted that terrestrialbiota not only adapts to environmental conditions but influences them through regulations on thechemical composition of the atmosphere. In the present study we used different methods to investigatethe relationship between the dimethyl sulphide (DMS), low clouds, Ultraviolet Radiation A (UVA) andSea Surface Temperature (SST) in the Southern Hemisphere, we found that the series analyzed havedifferent periodicities which are associated with weather and solar phenomena such as El Nino (ENSO),Quasi-Biennial Oscillation in the Stratosphere (QBO) and the average changes in solar activity. Wealso found that some series show persistence with which we can make predictions for the future of thesame trend.

E-mail: [email protected]

101 3-7 October 2011 – Mendoza, Argentina

Page 109: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

The Coronae of Ca II HK-Selected Magnetic Grand Minimum Can-didate Stars

S. H. Saar, P. Testa


Abstract. We use a recent method (Saar 2011) for identifying candidate stars in magnetic grandminima, which is based on a combination of their mean Ca II HK emission levels as a function ofmetallicity, and the variability of these levels, compared to other dwarfs. A sample of the brighter ofthese stars has now been studied with Chandra. We present initial results on the X-ray properties ofthese stars and compare them with the Sun and other low activity stars.

E-mail: [email protected]

102 3-7 October 2011 – Mendoza, Argentina

Page 110: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Seeing Measurement at Sasahuine Mountain, Moquegua, Peru

M. Huaman Espinoza, W. Guevara Day, E. Meza, J. Samanes, P. Becerra, C. Ferradas Alva

Comision Nacional de Investigacion y Desarrollo Aeroespacial, Peru

Abstract. One of the greatest factors that affect significantly the quality of astronomical images isthe atmospheric turbulence causing what we call ”seeing”. If there were not a terrestrial atmospherenor interstellar dust between an external source of radiation (eg. a celestial body) and our telescope(on Earth), this radiation would reach the telescope and form a diffraction pattern called Airy disk,due only to the optical effects on the telescope (because of the light diffracting and producing apattern with concentric dark and bright rings around the objects image). In Astronomy this ”seeing”is quantified using the stellar profile, measuring the full width at half maximum (FWHM) which isthe angular size of the image of a star with half the peak intensity level. This is a compilation ofthe work done to date on reduction and photometry of astronomical images using IRAF, obtainingpreliminary measurements of ”seeing” in the Sasahuine mountain astronomical site, located high inthe department of Moquegua (4511 meters above sea level ), in the town of Cambrune. To validatethis place for astronomical observation meteorological and sky quality measurements were made, beingthis the aim of our study. The present work is part of a bigger investigation which seeks to evaluatepotential astronomical observation sites in the Peruvian territory by executing missions called JANAX.These missions main objective is to gather data to validate the place for the future construction of aNational Astronomical Observatory

E-mail:[email protected]

103 3-7 October 2011 – Mendoza, Argentina

Page 111: Abstracts IAUS286

IAU Symposium 286 Comparative Magnetic Minima: Characterizing Quiet Times in the Sun and Stars

Installation and Operation of the Water Cherenkov Detector for theLarge Aperture GRB Observatory (LAGO)

L. J. Otiniano Ormachea, E. Tueros Cuadros, W. Guevara Day (LAGO collaboration)

Comision Nacional de Investigacion y Desarrollo Aeroespacial, Peru

The Large Aperture GRB Observarory is a continental-wide observatory devised to detect high energy(around 100 GeV) component of Gamma Ray Bursts (GRB), by using the single particle technique inarrays of Water Cherenkov Detectors (WCD) at high mountains sites of Argentina, Bolivia, Colombia,Costa Rica, Mexico, Venezuela and Peru. Details of the installation and operation of the detectors inMarcapomacocha in Peru at 4550 m a.s.l are given. Also a calibration method of the detector will bepresent.

E-mail:[email protected]

104 3-7 October 2011 – Mendoza, Argentina

Page 112: Abstracts IAUS286

Author List

Page 113: Abstracts IAUS286

• Mangalathayil Abdu, p. 44.

• Ximena Abrevaya, p. 67.

• Sant Agrawal, p. 77.

• Hala Al Jassar, p. 88.

• Rainer Arlt, p. 7.

• Laura Balmaceda, p. 79, p. 92.

• Paul Barklem, p. 94.

• Inez Batista, p. 44.

• Patricio Becerra, p. 103.

• Alessandro Bemporad, p. 32.

• Xavier Bertou, p. 83.

• Cesar Bertucci, p. 66.

• John Bieber, p. 88.

• Benjamin Brown, p. 10.

• Volker Bothmer, p. 68.

• Axel Brandenburg, p. 6, p. 8, p. 12, p. 33,p. 72, p. 73.

• Eckhard Bosman, p. 68.

• Matthew Browning, p. 10.

• Christiano Brum, p. 44.

• Allan Sacha Brun, p. 5, p. 10, p. 15.

• Andrea Buccino, p. 55, P. 100.

• Simon Candelaresi, p. 8.

• Claudia Candido, p. 44.

• Abraham Chian, p. 72.

• Arnab Choudhuri, p. 61, p. 63.

• Carolina Cincunegui, p. 55.

• Rodolfo G. Cionco, p. 97.

• Edward Cliver, p. 37.

• Rosa Compagnucci, p. 55.

• Deysi V. Cornejo Espinoza, p. 94.

• Pedro Corona Romero, p. 34.

• Eduardo Corton, p. 67.

• Joaquim Costa, p. 23.

• Hebe Cremades, p. 31, p. 79.

• German Cristiani, p. 90.

• Ruby M. Cuervo Osses, p. 54.

• Marlos da Silva, p. 88.

• Alisson Dal Lago, p. 76, p. 88, p. 90.

• Sergio Dasso, p. 30, p. 31, p. 35, p. 83.

• Giuliana de Toma, p. 24, p. 42.

• Fabio del Sordo, p. 12.

• Jose C. del Toro Iniesta, p. 29.

• Pascal Demoulin, p. 30, p. 87.

• Marc DeRosa, p. 15.

• Rodrigo Dıaz, p. 55.

• Mausumi Dikpati, p. 73.

• Marcus Duldig, p. 88.

• Vidyia C. Dwivedi, p. 77.

• Ezequiel Echer, p. 41, p. 98.

• Tatiana Egorova, p. 43.

• Barbara Emery, p. 42.

• Yvonne Elsworth, p. 17, p. 42.

• Robert Erdelyi, p. 81.

• Cristian Ferradas Alva, p. 103.

• Andre Fehlmann, p. 20.

• Wolfgang Finsterle, p. 20.

• Juan Fontenla, p. 21.

• Richard Frazin, p. 26, p. 85.

• Mark Giampapa, p. 46.

• Sarah Gibson, p. 42.

Page 114: Abstracts IAUS286

• Carlos Gimenez de Castro, p. 23.

• Walter Gonzalez, p. 41, p. 88, p. 98.

• J. Americo Gonzalez Esparza, p. 34.

• Gustavo Guerrero, p. 11, p. 73.

• Walter Guevara Day, p. 94, p. 103, p. 104.

• Madhulika Guhathakurta, p. 60.

• Adriana Gulisano, p. 30.

• Heidy Gutierrez, p. 78.

• Margit Haberreiter, p. 22.

• Frank Hill, p. 14, p. 18.

• J. Todd Hoeksema, p. 15.

• Kazuho Horiuchi, p. 70.

• Rachel Howe, p. 18.

• Mariela Huaman Espinoza, p. 103.

• Zhenguang Huang, p. 26, p. 85.

• John Humble, p. 88.

• Neal Hurlburt, p. 28.

• Emre Isik, p. 50.

• Jose Ishitsuka, p. 75, p. 91.

• Mutsumi Ishitsuka, p. 75, p. 91.

• Carla Jacobs, p. 32.

• Lan Jiang, p. 36.

• Emiliano Jofre, p. 100.

• Petri Kapyla, p. 11.

• Bidya B. Karak, p. 63.

• Chihiro Kato, p. 88.

• H. Kato, p. 70.

• James Klimchuk, p. 80.

• Zoltan Kollath, p. 99.

• Rudolf Komm, p. 18.

• Heidi Korhonen, p. 47.

• Takao Kuwabara, p. 88.

• Timothy Larson, p. 18.

• R. Leamon, p. 42.

• Christina Lee, p. 36.

• Jiuhou Lei, p. 42.

• Jeffrey Linsky, p. 49.

• Robert Lionello, p. 27.

• Fernando Lopez, p. 79.

• Ramon Lopez, p. 38.

• Marcelo Lopez Fuentes, p. 80, p. 87.

• Janet Luhmann, p. 36.

• Marialejandra Luna Cardozo, p. 81.

• Marıa Luisa Luoni, p. 55.

• Ward Manchester IV, p. 26, p. 85.

• Cristina H. Mandrini, p. 31, p. 87, p. 90.

• Georgeta Maris, p. 82, p. 86.

• Ovidiu Maris, p. 82.

• Eckart Marsch, p. 35.

• Petrus Martens, p. 13.

• Lurdes Martınez Meneses, p. 75.

• Valentın Martınez Pillet, p. 28.

• Jimmy Masıas Meza, p. 83.

• Hidefumi Matsuzaki, p. 70.

• William Matthaeus, p. 35.

• Pablo Mauas, p. 21, p. 55, p. 67, p. 93, p.100.

• Scott McIntosh, p. 42.

• Mario Melita, p. 100.

• Blanca Mendoza Ortega, p. 65, p. 101.

• Erik Meza, p. 103.

Page 115: Abstracts IAUS286

• Richard Mewaldt, p. 42.

• Marilena Mierla, p. 32, p. 82, p. 86.

• Mark Miesch, p. 10.

• Dhrubaditya Mitra, p. 33.

• Zoran Mikic, p. 27.

• Hiroko Miyahara, p. 70.

• Hideaki Motoyama, p. 70.

• Kazuoki Munakata, p. 39, p. 88.

• Andres Munoz Jaramillo, p. 13.

• Guadalupe Munoz Martınez, p. 84.

• Dibyendu Nandi, p. 9, p. 13.

• Daniel Nordemann, p. 98.

• Federico Nuevo, p. 85.

• Vladimir Obridko, p. 82, p. 86.

• Terry Onsager, p. 42.

• Katalin Olah, p. 48, p. 99.

• Constantin Oprea, p. 82, p. 86.

• Jaime A. Osorio Rosales, p. 101.

• Luis Otiniano Ormachea, p. 104.

• Etienne Pariat, p. 87.

• Romina Petrucci, p. 100.

• Gordon Petrie, p. 36.

• Giovanni Pinzon Estrada, p. 54.

• Stefan Poedts, p. 32.

• Mariano Poisson, p. 87.

• Dmitri Ponyavin, p. 19.

• Katja Poppenhager, p. 58.

• Jacov Portnoy, p. 52.

• Eric Priest, p. 1.

• Michael Proctor, p. 72.

• Ivan Ramırez, p. 94.

• Seth Redfield, p. 49.

• Erico Rempel, p. 72.

• Matthias Rempel, p. 18.

• Oscar A. Restrepo Gaitan, p. 54.

• Matthias Rheinhardt, p. 73.

• Nivaor Rigozo, p. 76, p. 98.

• Pete Riley, p. 27, p. 36, p. 42.

• Jenny M. Rodrıguez Gomez, p. 54.

• Paolo Romano, p. 74.

• Eugene Rozanov, p. 43.

• Marıa Emilia Ruiz, p. 35.

• Christopher Russell, p. 36.

• Steven Saar, p. 57, p. 95, p. 102.

• Ismail Sabbah, p. 88.

• Carolina Salas Matamoros, p. 89.

• Jorge Samanes, p. 103.

• Jurgen Schmitt, p. 51, p. 58.

• Werner Schmutz, p. 20, p. 43.

• Jesper Schou, p. 18.

• Karel Schrijver, p. 59.

• Nelson Schuch, p. 76, p. 88.

• Martın Schwartz, p. 100.

• Caius Selhorst, p. 23, p. 92.

• Alexander Shapiro, p. 43.

• Madan Sharma, p. 88.

• P. Shearer, p. 26.

• Kiyoto Shibasaki, p. 23.

• G. Sobko, p. 62.

• Sami Solanki, p. 64.

• Dmitry Sokoloff, p. 62.

Page 116: Abstracts IAUS286

• Mariza Souza Echer, p. 98.

• Raphael Steinitz, p. 52.

• Marcel Sutter, p. 20.

• Leif Svalgaard, p. 3, p. 23.

• Natalia S. Szajko, p. 90.

• Lela Taliashvili, p. 78, p. 89.

• Maurizio Ternullo, p. 74.

• Raul Terrazas Ramos, p. 91.

• Paola Testa, p. 95, p. 102.

• Barbara Thompson, p. 42.

• Michael Thompson, p. 2, p. 18.

• Viacheslav Titov, p. 27.

• Dadan Tiwari, p. 77.

• Andrey Tlatov, p. 25.

• Fuyuki Tokanai, p. 70.

• Juri Toomre, p. 10.

• Bruce Tsurutani, p. 41.

• Hugo Trigoso, p. 75, p. 91.

• Vladimir Trukhin, p. 62.

• Edith Tueros Cuadros, p. 104.

• Ilya Usoskin, p. 64.

• Jose Valdes Galicia, p. 40, p. 84.

• Adriana Valio, p. 23, p. 53, p. 92.

• Lidia van Driel-Gesztelyi, p. 48, p. 99.

• Jose Vaquero, p. 99.

• Bernardo Vargas, p. 40.

• Alberto Vasquez, p.26, p. 85.

• Gary Verth, p. 81.

• Lucas Ramos Vieira, p. 76.

• Mariela C. Vieytes, p.21, p. 93.

• Joern Warnecke, p. 33.

• James Weygand, p. 35.

• Brian Wood, p. 49.

• Yasuhiko Yamaguchi, p. 70.

• Yusuke Yokoyama, p. 70.

• V. Zadkov, p. 62.

• Liang Zhao, p. 42.

• Nadezhda Zolotova, p. 19.

• Francesca Zuccarello, p. 32.

• Francesco Zuccarello, p. 32.

Page 117: Abstracts IAUS286

Symposium participants

Page 118: Abstracts IAUS286

• Ximena Abrevaya, [email protected]

• Rainer Arlt, [email protected]

• Laura Balmaceda, [email protected]

• Inez Batista, [email protected].

• Cesar Bertucci, [email protected]

• Volker Bothmer, [email protected]

• Axel Brandenburg, [email protected]

• Matthew Browning, [email protected]

• Allan Sacha Brun, [email protected]

• Simon Candelaresi, [email protected]

• Abraham Chian, [email protected]

• Arnab Choudhuri, [email protected]

• Rodolfo G. Cionco, [email protected]

• Edward Cliver, [email protected]

• Deysi V. Cornejo Espinoza, [email protected]

• Pedro Corona Romero, [email protected]

• Hebe Cremades, [email protected]

• Maximiliano Crescitelli, [email protected]

• German Cristiani, [email protected]

• Ruby M. Cuervo Osses, [email protected]

• Marlos da Silva, [email protected]

• Alisson Dal Lago, [email protected]

• Sergio Dasso, [email protected]

• Giuliana de Toma, [email protected]

• Fabio del Sordo, [email protected]

• Jose C. del Toro Iniesta, [email protected]

• Marc DeRosa, [email protected]

• Vidyia C. Dwivedi, [email protected]

• Ezequiel Echer, [email protected]

• Yvonne Elsworth, [email protected]

Page 119: Abstracts IAUS286

• Cristian Ferradas Alva, [email protected]

• Romina Garcıa, rominita [email protected]

• Mark Giampapa, [email protected]

• Sarah Gibson, [email protected]

• Daniel Gomez, [email protected]

• Gustavo Guerrero, [email protected]

• Madhulika Guhathakurta, [email protected]

• Heidy Gutierrez, [email protected]

• Margit Haberreiter, [email protected]

• Frank Hill, [email protected]

• Neal Hurlburt, [email protected]

• Francisco Iglesias, [email protected]

• Emre Isik, [email protected]

• Laurene Jouve, [email protected]

• Bidya B. Karak, bidya [email protected]

• Heidi Korhonen, [email protected]

• Jon Linker, [email protected]

• Jeffrey Linsky, [email protected]

• Fernando Lopez, [email protected]

• Ramon Lopez, [email protected]

• Marcelo Lopez Fuentes, [email protected]

• Janet Luhmann, [email protected]

• Marialejandra Luna Cardozo, [email protected]

• Marıa Luisa Luoni, [email protected]

• Cristina H. Mandrini, [email protected]

• Lurdes Martınez Meneses, [email protected]

• Pablo Mauas, [email protected]

• Eduardo Mendoza, [email protected]

• Blanca Mendoza Ortega, [email protected]

• Hiroko Miyahara, [email protected]

Page 120: Abstracts IAUS286

• Kazuoki Munakata, [email protected]

• Andres Munoz Jaramillo, [email protected]

• Guadalupe Munoz Martınez, [email protected]

• Dibyendu Nandi, [email protected]

• Federico Nuevo, [email protected]

• Constantin Oprea, [email protected]

• Jaime A. Osorio Rosales, [email protected]

• Romina Petrucci, [email protected]

• Giovanni Pinzon Estrada, [email protected]

• Mariano Poisson, [email protected]

• Katja Poppenhager, [email protected]

• Eric Priest, [email protected]

• Oscar A. Restrepo Gaitan, [email protected]

• Matthias Rheinhardt, [email protected]

• Jenny M. Rodrıguez Gomez, [email protected]

• Eugene Rozanov, [email protected]

• Marıa Emilia Ruiz, [email protected]

• Steven Saar, [email protected]

• Carolina Salas Matamoros, [email protected]

• Jurgen Schmitt, [email protected]

• Werner Schmutz, [email protected]

• Karel Schrijver, [email protected]

• Caius Selhorst, [email protected]

• Dmitry Sokoloff, [email protected]

• Raphael Steinitz, [email protected]

• Leif Svalgaard, [email protected]

• Natalia S. Szajko, [email protected]

• Lela Taliashvili, [email protected]

• Maurizio Ternullo, [email protected]

• Raul Terrazas Ramos, [email protected]

Page 121: Abstracts IAUS286

• Michael Thompson, [email protected]

• Andrey Tlatov, [email protected]

• Edith Tueros Cuadros, [email protected]

• Ilya Usoskin, [email protected]

• Adriana Valio, [email protected]

• Jorge F. Valle Silva, [email protected]

• Lidia van Driel-Gesztelyi, [email protected]

• Jose Vaquero, [email protected]

• Bernardo Vargas, [email protected]

• Alberto Vasquez, [email protected]

• Mariela C. Vieytes, [email protected]

• Joern Warnecke, [email protected]

• David Webb, [email protected]

• Nadezhda Zolotova, [email protected]

• Francesco Zuccarello, [email protected]