11

The Real The Real

Music of the SpheresMusic of the Spheres

AsteroseismologyAsteroseismology

22

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?

55

66

3D oscillations – stars3D oscillations – starsradial modesradial modes

CepheidsP1/P0= 0.7

stringP1/P0= 0.33

77

Cepheid variablesCepheid variables

Cepheid Horn by Zoltan Kollath & Geza Kovács, Konkoly Observatory, Budapest; Robert Buchler, Florida

88

A giant solar-like oscillatorA giant solar-like oscillator

http://www.lcse.umn.edu/

99

AsteroseismologyAsteroseismology

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,

1111

1212

Dipole modesDipole modes

immm ePY cos, 11

l=1, m=0 l=1, m=+1l=1, m=-1

1313

immm ePY cos, 22

l=2, m=-1l=2, m=-2 l=2, m=0

Quadrupole modesQuadrupole modes

1414

Rotation of the sunRotation of the sun

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

1717

The sun as a star - BiSONThe sun as a star - BiSON

1818

0 2n n

The sun as a star - GOLFThe sun as a star - GOLF

large separation small separation

1919

An asteroseismic HR diagramAn asteroseismic HR diagram

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

2424

2525

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

3030

3131

3232

Theoretical expectationTheoretical expectation

Saio, 2005, MNRAS, 360, 1022

= 0.7 = 0.1

3333

HD 101065HD 101065

BaII NdIII

3434

~ 10-5

~ 10-2

3535

HD99563HD99563

3636

~ 10-5

~ 10-2

~ 10-5

<< 10-5

3737

Gautschy, Saio & Harzenmoser, 1998, MNRAS, 301, 31

3838

3939

4040

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

4444

White dwarfs – gWhite dwarfs – g--mode pulsatorsmode pulsators

4545

PG 1159-035

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

4848

BPM 37093BPM 37093

4949

p modes: EC 14026 stars - sdBVp modes: EC 14026 stars - sdBV

5050

PG 1336 + 018PG 1336 + 018

5151

p modes: p modes: Cephei stars Cephei stars

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

5353

g modes: SPB starsg modes: SPB stars

5454

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

5757

Dome C - ConcordiaDome C - Concordia

5858

5959

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)

6161

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?

6363

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

6868

HR 1217HR 1217photometric campaignsphotometric campaigns

6969

HR 1217HR 1217photometric campaignsphotometric campaigns