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Sir Arthur Stanley Eddington:The Internal Constitution of the Stars
1926
At first sight it would seem At first sight it would seem that the deep interior that the deep interior of the sun and stars of the sun and stars
is less accessible is less accessible to scientific investigation to scientific investigation
than any other region of the than any other region of the universe.universe.
Sir Arthur Eddington (1882 – 1944)
33
Our telescopes may probe Our telescopes may probe farther and farther farther and farther
into the depths of space; into the depths of space; but how can we ever obtain but how can we ever obtain
certain knowledge certain knowledge of that which is hidden of that which is hidden
behind substantial barriers?behind substantial barriers?
44
What appliance What appliance can pierce through can pierce through
the outer layers of a star the outer layers of a star and test and test
the conditions within?the conditions within?
66
3D oscillations – stars3D oscillations – starsradial modesradial modes
CepheidsP1/P0= 0.7
stringP1/P0= 0.33
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Cepheid variablesCepheid variables
Cepheid Horn by Zoltan Kollath & Geza Kovács, Konkoly Observatory, Budapest; Robert Buchler, Florida
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A giant solar-like oscillatorA giant solar-like oscillator
http://www.lcse.umn.edu/
1010
Angular structure of the modesAngular structure of the modes
nn = = number of radial nodesnumber of radial nodes = = total number of surface nodestotal number of surface nodes mm = = number of surface nodes that are lines number of surface nodes that are lines
of longitudeof longitude – – m = m = number of surface nodes that are number of surface nodes that are
lines of latitudelines of latitude
immmm ePNY cos,
1515
p modes and g modesp modes and g modes
J. P. Cox, 1980, Theory of Stellar Pulsation, Princeton University Press.
1616
p modes and g modesp modes and g modes
p modes (n,) = (8,100), (8,2)
g mode (n,) = (10,5)
Gough et al., 1996, Science, 272, 1281
2020
Solar-like Oscillations in Solar-like Oscillations in Centauri Centauri
UVES & UCLESUVES & UCLES 42 oscillation frequencies42 oscillation frequencies ℓℓ = 1-3= 1-3 Mode lifetimes only Mode lifetimes only
1-2 days1-2 days Noise level = 2 cm sNoise level = 2 cm s-1-1!!
Bedding, T., et al. 2004, ApJ, 614, 380
2121
Modelling Modelling Cen A and B Cen A and B Stellar model in good agreement with the Stellar model in good agreement with the
astrometric, photometric, spectroscopic and astrometric, photometric, spectroscopic and asteroseismic data asteroseismic data
t = 6.52 ± 0.30 Gyrt = 6.52 ± 0.30 Gyr Initial Y = 0.275 ± 0.010 Initial Y = 0.275 ± 0.010 Initial Z/X = 0.043 ± 0.002Initial Z/X = 0.043 ± 0.002 Radii of both stars determined with Radii of both stars determined with
high precision (errors smaller than 0.3%)high precision (errors smaller than 0.3%) compatible with interferometric results of compatible with interferometric results of
Kervella et al. (differences smaller than 1%)Kervella et al. (differences smaller than 1%)
Eggenberger, P., Charbonnel, C., Talon, S., Meynet, G., Maeder, A., Carrier, F., Bourban, G. 2004, A&A, 417, 235
2222
Oscillations and planetsOscillations and planets Stellar activity, convection and pulsation are Stellar activity, convection and pulsation are
“noise” to planet-hunters“noise” to planet-hunters
Planets are “noise” to asteroseismologistsPlanets are “noise” to asteroseismologists
The two fields are not just complementaryThe two fields are not just complementary
It is mandatory to do both together atIt is mandatory to do both together atcm scm s-1-1 precision precision
2323
AraeArae
V = 5.15V = 5.15 G3IV-VG3IV-V
PProtrot = 22 days = 22 days
14 M14 M planet; P planet; Porborb = 9.55 days = 9.55 days
43 p-modes detected43 p-modes detected 8-day single-site HARPS study8-day single-site HARPS study
Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
2626
Arae – the Arae – the 14 M14 M planet planet
Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
2727
Arae – ~8-min pulsationsArae – ~8-min pulsations
Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
2828
AraeArae
Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
2929
Resolving pulsations Resolving pulsations
in the atmospheresin the atmospheres
of roAp starsof roAp stars
Don KurtzDon KurtzVladimir ElkinVladimir Elkin
Gautier MathysGautier Mathys
4141
HD154708HD154708
Hubrig, S., Nesvacil, N., Schöller, M., North, P., Mathys, G., Kurtz, D. W., Wolff, B., Szeifert, T., Cunha, M. S., Elkin, V. G., 2005, A&A, 440, L37
4242
HD154708HD154708
Kurtz, D. W., Elkin, V. G., Elkin, V. G., Mathys, G., Hubrig, Wolff, B., Savanov, I., 2006, MNRAS, submitted
4343
We are seeing the roAp staratmospheres
in more detail than is possiblefor any star
other than the sun
4646
TTsurfsurf = 123,000 - 124,000 K; log g = 123,000 - 124,000 K; log g 7 7
1000 1000 f f 2600 2600 Hz; 385 Hz; 385 P P 1000 1000
ss
125 frequencies; >100 modes125 frequencies; >100 modes
M = 0.586 ± 0.003 M = 0.586 ± 0.003 MM
the star is compositionally stratifiedthe star is compositionally stratified
PG 1159-035PG 1159-035
4747
BPM 37093BPM 37093 DAVDAV
M = 1.09 M = 1.09 MM
TTeffeff = 11730 K = 11730 K
Partially crystallized Partially crystallized
C-O coreC-O core
Metcalfe, T. S., Montgomery, M. H., Kanaan, A. 2004, ApJ, 605, 133
Kanaan et al., 2005, A&A, 432, 219
Brassard & Fontaine, 2005, ApJ, 622, 572
5252
HD 129929 = V836 Cen HD 129929 = V836 Cen 20-yr multicolour photometry
Core overshooting with aOV = 0.1
Non-rigid rotation: 4 times faster near core
Aerts et al., 2003, Science, 300, 926 Asteroseismology of HD129929: Core overshooting and nonrigid rotation
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Continuous coverage - MOSTContinuous coverage - MOST
HD163830 HD163830 SPB starSPB star V = 9.3V = 9.3 B5II/IIIB5II/III 37 days coverage37 days coverage 20 frequencies 20 frequencies
detecteddetected
5555
HD 163830HD 163830
Aerts, C.; De Cat, P.; Kuschnig, R.; Matthews, J. M.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Walker, G. A. H.; Weiss, W. W., 2006, ApJ, 642, L65
5656
HD 163830HD 163830
Aerts, C.; De Cat, P.; Kuschnig, R.; Matthews, J. M.; Guenther, D. B.; Moffat, A. F. J.; Rucinski, S. M.; Sasselov, D.; Walker, G. A. H.; Weiss, W. W., 2006, ApJ, 642, L65
6060
Seeing 2003-2004: statisticsSeeing 2003-2004: statistics
0.100.10 Seeing minSeeing min0.540.54Median seeingMedian seeing
5.225.22 Seeing maxSeeing max0.650.65Mean seeing (arcsec)Mean seeing (arcsec)
0.390.39 Std deviationStd deviation1714817148N dataN data
1 30.30.1
50%
0.50.5
Seeing distribution (log-normal)
6262
What appliance What appliance can pierce through can pierce through
the outer layers of a star the outer layers of a star and test and test
the conditions within?the conditions within?
6464
Stellarmusicno1Stellar acoustics as input for music compositionStellar acoustics as input for music composition
Zoltán KolláthZoltán KolláthKonkoly Observatory, Budapest, HungaryKonkoly Observatory, Budapest, Hungary
Jenő KeulerJenő KeulerInstitute for Musicology, Budapest, HungaryInstitute for Musicology, Budapest, Hungary
http://www.konkoly.hu/staff/kollath/stellarmusic/
6565
Photometry - HR 1217 WET Xcov20Photometry - HR 1217 WET Xcov20
Kurtz et al., 2005, MNRAS, 358, 651
= 14 magprecision
6666
What can you do with the frequencies What can you do with the frequencies in roAp stars? – HR 1217in roAp stars? – HR 1217
6767
A model and predictionA model and prediction
Cunha, M. 1999, PhD thesis, CambridgeCunha, M. 1999, PhD thesis, CambridgeCunha, M. Gough, D., 2001, MNRAS, 319, 1020Cunha, M. Gough, D., 2001, MNRAS, 319, 1020Bigot et al. 2000, A&A, 356, 218Bigot et al. 2000, A&A, 356, 218