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Astron. Astrophys. 351, 582-596 (1999)


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Amplitudes of stochastically excited oscillations in main-sequence stars

G. Houdek 1,2, N.J. Balmforth 3, J. Christensen-Dalsgaard 4 and D.O. Gough 1,5

1 Institute of Astronomy, University of Cambridge, Cambridge CB3 0HA, UK
2 Institut für Astronomie, Universität Wien, 1180 Wien, Austria (hg@ast.cam.ac.uk)
3 Instituto di Cosmogeofisica, Corso Fiume 4, Torino 10133, Italy (njb@hank.ucsd.edu)
4 Teoretisk Astrofysik Center, Danmarks Grundforskningsfond, and Institut for Fysik og Astronomi, Aarhus Universitet, 8000 Aarhus C, Denmark (jcd@obs.aau.dk)
5 Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 9EW, UK (douglas@ast.cam.ac.uk)

Received 10 May 1999 / Accepted 7 September 1999

Abstract

We present estimates of the amplitudes of intrinsically stable stochastically excited radial oscillations in stars near the main sequence. The amplitudes are determined by the balance between acoustical energy generation by turbulent convection (the Lighthill mechanism) and linear damping. Convection is treated with a time-dependent, nonlocal, mixing-length model, which includes both convective heat flux and turbulent pressure in both the equilibrium model and the pulsations. Velocity and luminosity amplitudes are computed for stars with masses between [FORMULA] and [FORMULA] in the vicinity of the main sequence, for various metallicities and convection parameters. As in previous studies, the amplitudes are found to increase with stellar mass, and therefore with luminosity. Amongst those stars that are pulsationally stable, the largest amplitudes are predicted for a [FORMULA] model of spectral type F2; the values are approximately 15 times larger than those measured in the Sun.

Key words: convection – turbulence – stars: oscillations

Send offprint requests to: G. Houdek

© European Southern Observatory (ESO) 1999

Online publication: November 3, 1999

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