The Real Music of the Spheres Asteroseismology The Real Music of the Spheres
Sir Arthur Stanley Eddington: The Internal Constitution of the Stars 1926 At first sight it would seem that the deep interior of the sun and stars is less accessible to scientific investigation than any other region of the universe. Sir Arthur Eddington (1882 – 1944)
Our telescopes may probe farther and farther into the depths of space; but how can we ever obtain certain knowledge of that which is hidden behind substantial barriers?
What appliance can pierce through the outer layers of a star and test the conditions within?
Asteroseismology
3D oscillations – stars radial modes Cepheids P1/P0= 0.7 string P1/P0= 0.33
Cepheid variables Cepheid Horn by Zoltan Kollath & Geza Kovács, Konkoly Observatory, Budapest; Robert Buchler, Florida
A giant solar-like oscillator http://www.lcse.umn.edu/
Asteroseismology
Angular structure of the modes n = number of radial nodes = total number of surface nodes m = number of surface nodes that are lines of longitude – m = number of surface nodes that are lines of latitude
Dipole modes l=1, m=-1 l=1, m=0 l=1, m=+1
Quadrupole modes l=2, m=-2 l=2, m=-1 l=2, m=0
Rotation of the sun
p modes and g modes J. P. Cox, 1980, Theory of Stellar Pulsation, Princeton University Press.
p modes and g modes p modes g mode (n,) = (8,100), (8,2) Gough et al., 1996, Science, 272, 1281
The sun as a star - BiSON
The sun as a star - GOLF large separation small separation
An asteroseismic HR diagram
Solar-like Oscillations in Centauri Bedding, T., et al. 2004, ApJ, 614, 380 UVES & UCLES 42 oscillation frequencies ℓ = 1-3 Mode lifetimes only 1-2 days Noise level = 2 cm s-1!
Modelling Cen A and B Stellar model in good agreement with the astrometric, photometric, spectroscopic and asteroseismic data t = 6.52 ± 0.30 Gyr Initial Y = 0.275 ± 0.010 Initial Z/X = 0.043 ± 0.002 Radii of both stars determined with high precision (errors smaller than 0.3%) compatible with interferometric results of 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
Oscillations and planets Stellar activity, convection and pulsation are “noise” to planet-hunters Planets are “noise” to asteroseismologists The two fields are not just complementary It is mandatory to do both together at cm s-1 precision
Arae V = 5.15 G3IV-V Prot = 22 days 14 M planet; Porb = 9.55 days 43 p-modes detected 8-day single-site HARPS study Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
Ara b : giant Msini = 1.67 Jupiter masses a = 1.5 AU Porb = 654.5 days e = 0.31 Ara c : giant Msini = 3.1 Jupiter masses a = 4.17 AU Porb = 2986 days e = 0.57 Ara d : ?? Msini = 14 Earth masses a = 0.09 AU Porb = 9.55 days e = 0
Arae – the 14 M planet Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
Arae – ~8-min pulsations Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
Arae Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
Resolving pulsations in the atmospheres of roAp stars Don Kurtz Vladimir Elkin Gautier Mathys
Theoretical expectation = 0.7 = 0.1 Saio, 2005, MNRAS, 360, 1022
HD 101065 BaII NdIII
~ 10-5 ~ 10-2
HD99563
~ 10-5 ~ 10-2 << 10-5
Gautschy, Saio & Harzenmoser, 1998, MNRAS, 301, 31
HD154708 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
HD154708 Kurtz, D. W., Elkin, V. G., Elkin, V. G., Mathys, G., Hubrig, Wolff, B., Savanov, I., 2006, MNRAS, submitted
We are seeing the roAp star atmospheres in more detail than is possible for any star other than the sun
White dwarfs – g-mode pulsators
PG 1159-035
PG 1159-035 Tsurf = 123,000 - 124,000 K; log g 7 1000 f 2600 Hz; 385 P 1000 s 125 frequencies; >100 modes M = 0.586 ± 0.003 M the star is compositionally stratified
BPM 37093 DAV M = 1.09 M Teff = 11730 K Partially crystallized C-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
BPM 37093
p modes: EC 14026 stars - sdBV
PG 1336 + 018
p modes: Cephei stars
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
g modes: SPB stars
Continuous coverage - MOST HD163830 SPB star V = 9.3 B5II/III 37 days coverage 20 frequencies detected
HD 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
HD 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
Dome C - Concordia
Seeing 2003-2004: statistics 0.10 Seeing min 0.54 Median seeing 5.22 50% 0.5 0.1 0.3 0.5 1 3 Seeing distribution (log-normal) 0.10 Seeing min 0.54 Median seeing 5.22 Seeing max 0.65 Mean seeing (arcsec) 0.39 Std deviation 17148 N data
What appliance can pierce through the outer layers of a star and test the conditions within? Asteroseismology
Stellarmusicno1 Stellar acoustics as input for music composition Zoltán Kolláth Konkoly Observatory, Budapest, Hungary Jenő Keuler Institute for Musicology, Budapest, Hungary http://www.konkoly.hu/staff/kollath/stellarmusic/
Photometry - HR 1217 WET Xcov20 = 14 mag precision Kurtz et al., 2005, MNRAS, 358, 651
What can you do with the frequencies in roAp stars? – HR 1217
A model and prediction Cunha, M. 1999, PhD thesis, Cambridge Cunha, M. Gough, D., 2001, MNRAS, 319, 1020 Bigot et al. 2000, A&A, 356, 218
HR 1217 photometric campaigns
HR 1217 photometric campaigns