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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.

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The Real Music of the Spheres

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  1. Asteroseismology The Real Music of the Spheres

  2. 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)

  3. 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?

  4. What appliance can pierce through the outer layers of a star and test the conditions within?

  5. Asteroseismology

  6. 3D oscillations – starsradial modes CepheidsP1/P0= 0.7 stringP1/P0= 0.33

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

  8. A giant solar-like oscillator http://www.lcse.umn.edu/

  9. Asteroseismology

  10. 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

  11. Dipole modes l=1, m=0 l=1, m=-1 l=1, m=+1

  12. Quadrupole modes l=2, m=-2 l=2, m=-1 l=2, m=0

  13. Rotation of the sun

  14. p modes and g modes J. P. Cox, 1980, Theory of Stellar Pulsation, Princeton University Press.

  15. g mode (n,) = (10,5) p modes (n,) = (8,100), (8,2) p modes and g modes Gough et al., 1996, Science, 272, 1281

  16. The sun as a star - BiSON

  17. The sun as a star - GOLF large separation small separation

  18. An asteroseismic HR diagram

  19. Bedding, T., et al. 2004, ApJ, 614, 380 Solar-like Oscillations in  Centauri • UVES & UCLES • 42 oscillation frequencies • ℓ = 1-3 • Mode lifetimes only 1-2 days • Noise level = 2 cm s-1!

  20. 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

  21. 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 atcm s-1 precision

  22.  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

  23.  Arae – the 14 M planet Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609

  24.  Arae – ~8-min pulsations Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609

  25.  Arae Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609

  26. Resolving pulsations in the atmospheresof roAp starsDon KurtzVladimir ElkinGautier Mathys

  27.  = 0.1  = 0.7 Theoretical expectation Saio, 2005, MNRAS, 360, 1022

  28. HD 101065 BaII NdIII

  29.  ~ 10-2  ~ 10-5

  30. HD99563

  31.  ~ 10-2  ~ 10-5  ~ 10-5  << 10-5

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

  33. 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

  34. HD154708 Kurtz, D. W.,Elkin, V. G.,Elkin, V. G.,Mathys, G.,Hubrig,  Wolff, B., Savanov, I., 2006, MNRAS, submitted

  35. We are seeing the roAp star atmospheres in more detail than is possible for any star other than the sun

  36. White dwarfs – g-mode pulsators

  37. PG 1159-035

  38. 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

  39. 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

  40. BPM 37093

  41. p modes: EC 14026 stars - sdBV

  42. PG 1336 + 018

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