Download presentation
1
The Real Music of the Spheres
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 – stars radial modes
Cepheids P1/P0= 0.7 string P1/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
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
12
Dipole modes l=1, m=-1 l=1, m=0 l=1, m=+1
13
Quadrupole modes l=2, m=-2 l=2, m=-1 l=2, m=0
14
Rotation of the sun
15
p modes and g modes J. P. Cox, 1980, Theory of Stellar Pulsation, Princeton University Press.
16
p modes and g modes p modes g mode (n,) = (8,100), (8,2)
Gough et al., 1996, Science, 272, 1281
17
The sun as a star - BiSON
18
The sun as a star - GOLF large separation small separation
19
An asteroseismic HR diagram
20
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!
21
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 = ± 0.010 Initial Z/X = ± 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
22
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
23
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
24
Ara b : giant Msini = 1.67 Jupiter masses a = 1.5 AU Porb = 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 = AU Porb = 9.55 days e = 0
26
Arae – the 14 M planet Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
27
Arae – ~8-min pulsations
Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
28
Arae Bouchy, F., Bazot, M., Santos, N. C., Vauclair, S., Sosnowska, D., 2005, A&A, 440, 609
29
Resolving pulsations in the atmospheres of roAp stars Don Kurtz Vladimir Elkin Gautier Mathys
32
Theoretical expectation
= 0.7 = 0.1 Saio, 2005, MNRAS, 360, 1022
33
HD BaII NdIII
34
~ 10-5 ~ 10-2
35
HD99563
36
~ 10-5 ~ 10-2 << 10-5
37
Gautschy, Saio & Harzenmoser, 1998, MNRAS, 301, 31
41
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
42
HD154708 Kurtz, D. W., Elkin, V. G., Elkin, V. G., Mathys, G., Hubrig, Wolff, B., Savanov, I., 2006, MNRAS, submitted
43
We are seeing the roAp star atmospheres
in more detail than is possible for any star other than the sun
44
White dwarfs – g-mode pulsators
45
PG
46
PG Tsurf = 123, ,000 K; log g 7 1000 f 2600 Hz; 385 P 1000 s 125 frequencies; >100 modes M = ± M the star is compositionally stratified
47
BPM 37093 DAV M = 1.09 M Teff = 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
48
BPM 37093
49
p modes: EC stars - sdBV
50
PG
51
p modes: Cephei stars
52
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
53
g modes: SPB stars
54
Continuous coverage - MOST
HD163830 SPB star V = 9.3 B5II/III 37 days coverage 20 frequencies detected
55
HD 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
56
HD 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
57
Dome C - Concordia
60
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
62
What appliance can pierce through the outer layers of a star and test the conditions within?
Asteroseismology
64
Stellarmusicno1 Stellar acoustics as input for music composition
Zoltán Kolláth Konkoly Observatory, Budapest, Hungary Jenő Keuler Institute for Musicology, Budapest, Hungary
65
Photometry - HR 1217 WET Xcov20
= 14 mag precision Kurtz et al., 2005, MNRAS, 358, 651
66
What can you do with the frequencies in roAp stars? – HR 1217
67
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
68
HR 1217 photometric campaigns
69
HR 1217 photometric campaigns
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.