Stellar Rotation in the CoRoT Era

Jose Dias do Nascimento Jr & José Renan de Medeiros

and team

DFTE- Natal Departamento de Física Teórica e Experimental, Brazil

2-6 November 2005

SECOND COROT- BRASIL WORKSHOP

Ubatuba, SP

AcRoCOROT Home Page http://ace.dfte.ufrn.br/corot/index.html

I. The Sun in Time: The History of the Solar Angular Momentum Evolution

II. Stellar rotation in CoRoT Era: The Stellar Angular Momentum History in HR Diagram

Accepted CoRoT Proposals:

Team of Proponents: I

J.R. De Medeiros(1), J.D.Jr Do Nascimento(1), G. Cutispoto(2) A. Domiciano de Souza(3) M.-J. Goupil(4) P. de Laverny(5) A.Lebre(6) A. Maeder(7) C.H.F. Melo(8) G.P. Mello(9) S. Messina(2) E.J. Pacheco(10) P.S. Parihar(14) L. Pasquini(8) E. Peloso(9) A. Recio-Blanco(5) A.I. Ribas(11) F. Royer(4) A. Silva(12) L. Silva(13)

1) Departamento de Física, U. Federal do Rio Grande do Norte, Brazil2) 0ssevatorio di Catania, Catania, Italy3) Max-Planck-Institute Bonn, Germany4) 0bservatoire de Paris, Meudon cedex, France5) 0bservatoire de Ia Cote d'Azur, Nice, France6) Groupe d'Astrophysique, U. de Montpellier, Montpellier, France7) 0bservatoire de Geneve, Switzerland8) European Southern Observatory9) 0bservatorio do Valongo, Rio de Janeiro, Brazil10) Universidade de São Paulo, São Paulo, Brazil11) Inlnstitut de Ciències de l'Espai (CSIC-IEEC), Barcelona, Spain12) Observatório Nacional, Rio de Janeiro, Brazil13) Universidade Mackenzie, São Paulo, Brazil14) Indian Institute of Astrophysics, Koramangala, Bangalore, índia

Team of Proponents: II

J.R. De Medeiros(1), J.D. Do Nascimento(1), C.H.F. Melo(7) A. Domiciano de Souza(2) M.-J. Goupil(3) A.-M. Hubert(3) G. Jasniewicz(5) P. de Laverny(4) A.Lebre(5) A. Maeder(6), G.P. Mello(8) E.J. Pacheco(9) L. Pasquini(7) E. Peloso(8) G. Quast(13) A. Recio-Blanco(4) F. Royer(4) L. Silva(11) A. Silva(12) C.A. Torres(13)

1) Departamento de Física, U. Federal do Rio Grande do Norte, Brazil2) Max-Planck-Institute Bonn, Germany3) 0bservatoire de Paris, Meudon cedex, France4) 0bservatoire de Ia Cote d'Azur, Nice, France5) Groupe d'Astrophysique, U. de Montpellier, Montpellier, France6) 0bservatoire de Geneve, Switzerland7) European Southern Observatory8) 0bservatorio do Valongo, Rio de Janeiro, Brazil9) Universidade de São Paulo, São Paulo, Brazil10) Institut de Ciències de 1'Espai (CSIC-IEEC), Barcelona, Spain11) Observatório Nacional, Rio de Janeiro, Brazil12) Universidade Mackenzie, São Paulo, Brazil13) Laboratorio Nacional de Astrofísica, MG, Brazil

I- The Sun in Time: The History of the Solar Angular Momentum

Evolution

Abstract:

On the basis of data for a statistically robust sample of stars from the CoRoT Exofield Long Runs, we intend to carry out an unprecedented study on the evolution of the solar angular momentum. The stars composing the sample have as main characteristics a solar metallicity and are located along the evolutionary track of 1.0 M0 on the different stages from the main sequence to the basis of the giant branch. The obtained rotational period will enable us to analyze the behavior of the rotation with age and the mechanisms playing a major role on the evolution of this fundamental parameter. From this information, for solar-like stars, it will be possible to write a comparative history of the angular momentum of the Sun ali along its life, from the main sequence to the red giant stages.

II- Stellar rotation in CoRoT Era: The Stellar Angular Momentum History

in HR Diagram

Abstract:

On the basis of CoRoT observations for a statistically robust sample of stars from the CoRoT Sismo and Exofield Long Runs, we intend to carry out an unprecedented study on the behavior of the stellar rotation along the HR diagram. Rotation period obtained from light modulation, combined with other stellar parameters, will enable us to analyze the behavior of rotation as a function of luminosity, mass, age and metallicity. From this study we hope to oífer solid constraints for models of stellar evolution, as well as for the study of mechanisms controlling activity and chemical mixing in different stages of the stellar evolution.

Scientific Motivation

Stellar Rotation is one of the most important observable in stellar astrophysics, driving largely the stellar evolution

- The Stellar Angular Momentum History in HR Diagram

- The link of rotation with stellar parameters

- The role of rotation on stellar internal and external phenomena

These two proposals are in fact complementary:

- Different timescales (from days to hundreds of days); - Optimized for different S/N of the data; - Similar techniques of time series analysis and modelling; - Dependence of rotation on stellar mass

In Fact, rotation is not an optional stellar astrophysical parameters…

Scientific MotivationQuestions:

• Is the sun typical for its mass and age ?• Has the presence of planets influenced rotation ?• How did the sun get where it is today ?

•Is the rotation indicative of sub-surface phenomena ?

- Differential rotation- Rotation and activity cycles- Rotation and mixing and A rapid rotation core ?

•Rotation versus chemical abundances•Rotation versus atmospheric emission fluxes•Rotation and binarity•Are the Stellar Axes distributed randomly ?

ROTATION AT ONE SOLAR MASS(some previous claims)

What we know about Stellar Rotatoin

• Kraft´s 67 Obvious drop in rotation at 1 Solar Mass and Activity stars are faster rotators

– late F dwarfs lose angular momentum during their main sequence life times.

• Skumanich´72 Quantified a relation t-1/2 for rotation, Ca II emission

ROTATION AT ONE SOLAR MASSMilestones

What we know about Stellar Rotatoin

• Soderbom´83 Rotation of late type stars and the rotational history of the sun. The t -1/2 relation cannot hold for stars much younger than the pleiades. Some open questions...

– Do 1.25 Solar Mass stars also follow a t -1/2 relation ?– Other Classes of stars as massive as the sun follow this

relation ?

• Pace and Pasquini 2004 Proposed a new t- relation on the basis of larger stellar sample than previous studies.

Skumanich (1972)

showed that Kraft’s Hyades and Pleiadesdata together with the rotational velocity of the Sun, were consistent with the relation v ~ t-1/2

So, Activity ~ Rotation

Prot

What we know about Stellar Period of Rotation Evolution ?

3.9 3.8 3.7 3.6 3.5-1

0

1

2

3

4

5

1,25 Mo 1 M

o

Vsini < 2 2 < Vsini < 7 7 < Vsini < 20 Vsini > 20

log

(L/L

o)

log (Teff

)

What we know about Stellar Rotation !

Evolution of Projected rotational velocities:

Distribution of

Vsini on the HR DiagramCORAVEL Measuremen

ts (De Medeiros Mayor

1999)

Tracks From do

Nacimento

et al. 1999Toulouse – GeneveEvolutionary

Code

What we know about Stellar Rotation !

Projected rotational velocities For 1 Msun

Evolution of Rotation Periods for FGK and M

Rotation Period for asample of about 1400 FGK and M stars from the MS to the turnoff;

Evolution of Rotation Periods for FGK & M

Rotational Period for a sample of about 1400 FGK and M stars from the MS to the turnoff;

Distribution of Rotational Periods

- The behavior of stellar Rotational Periods for Main Sequence Stars

-100 -50 0 50 100 150 200 250 300 350 400 450 500 550 6000

10

20

30

40 Rotational Periods forSolar Analogs whith d < 25 pc

Period (Days)

0 10 20 30 40 50 60 700

10

20

30

40

50

60

70

80

90

100

110

120

Period (days)

1200 Periods forFGK and M

(Do Nascimento and De Medeiros 2005)

Impact of high-precision

(up to 150 days) observations!!!

(Do Nascimento and De Medeiros 2005)

M67 solar-age open cluster: a laboratory for the Sun in time

(see Poster No 1 by Canto-Martins et al.)

Color-magnitude diagram of the open cluster M67

Stars composing our sample are labeled with red cross symbols.

Rotation, activity diagnostics, chemical abundances and single or multiplicity status for all the stars

What family of stars we plan to observe with CoRoT

F, G and K spectral type stars, following defined evolutionary tracks

Stars with previously defined parameters

Stars with single or multiple previously defined status

Seismology

Long runs (150 days)

• accurate spectrum analysis

• main sequence A, F, G

• targets of solar mass, Scuti, Dor, Cep…

Short runs (20 days)

• Processes across the HR diagram

Exofield • red dwarfs

• spectral types F to M

-5

0

+5

+10

+15

Mv

Temperature (spectral type)

Dor

Scuti

Ceph

sdB

Solar type

RR Lyrae

O B A F G K M

CepheidsSPB

Giants

Main sequencePriority targets for seismology

Targets for exoplanet search

From Laurent Boisnard 1st Brazil COROT Workshop, Natal, 30 Oct 2004

What we need to obtain from CoRoT measurements

30 50 100 200 300 600 800 4.5Gyr

70 60 50 40 30 20 10 0

AGE (Myr)

SUN

Prot(days)- High-precision as possible,(F/F ~ 10-4 - 10-3) observations

Stars with apparent Visual Magnitudes 12 < V < 12.5 (ground observations

with high signal to noise spectra ) Claudio Melo’s Talk

Observations in Short runs (20 days) and long runs (150 days) to study the processes across the HR diagram.

Light curves : Baudin et al simulator

Including photon and granulation noise …

Expected (most important) difficulties

I) Precise determination of stellar parameters to characterization of the sample (procedures by Recio-Blanco et al. (2005) and Silva et al. (2005))

II) Multiplicity, including planet effects

III) Spotted stars

Stellar Chemical Abundances and Atmospheric Parameters from the Gaia/RVS

spectra

A. Recio-Blanco

(in collaboration with P. de Laverny, A. Bijaoui)

Laboratoire CassiopéeObservatoire de la Côte d’Azur (France)

The algorithm: MATISSE – B functions

Grid of synthetic spectra

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

●

Teff

log g

[M/H]

● Dimensions: -Atmospheric parameters:

Teff, log g, [M/H]

-[/Fe]

-[Ca/H], [Mg/H], [Si/H], [Ti/H],…

Si (λ) MARCS

collaboration

Stellar Chemical Abundances and Atmospheric Parameters from the Gaia/RVS

spectra

Preparatory and followup stages and CoRoT data center at Natal

• Official Brazil/Chile program to use chilean telescope time by the AcRoCoRoT Team (talk by Claudio Melo)

• CoRoT Data Center at Natal conducted and operated by Departamento de Informática e Matemática Aplicada - UFRN, supported by CNPq, CAPES and FAPERN in collaboration with INPE (Brazilian Center of Missions at Natal)

Expected COROT samples

we can estimate:

- About 220 objects with 11<V<12.5 in the F to K spectral range - exp. accuracy: (100-150)•10-6 in 1-hr integration time;

- We estimate from the Hipparcos photometry, that about 200 F-K stars with some variability (about 10-2 mag. or larger)

See the poster SAMPLE SELECTION FOR THE ACCEPETD PROPOSAL: The Sun in Time. (Peloso et al.)

Conclusions

COROT will provide us with an new and solid view of STELLAR ROTATION across the HR diagram.

Our results will have an impact also on the core program and other additional science proposals, e.g.,

- Magnetic activity- Oscillations - Microvariability- Binarity ...

" CoRoT mission means also the harmonization and solidarity among people,  represented by greater symbols of the human intelligence: their   academic institutions and their achievements "

José Ivonildo Rêgo

Rector / Federal University of Rio Grande do Norte 

Thank you!!

AcRoCOROT Home Page http://ace.dfte.ufrn.br/corot/index.html

End

What we know about the Angular Momentum Evolution ?

The angular momentum per gram

as a function

of Log M.