New light on the driving mechanism in roAp stars: I. Effects of metallicity
Théado, Sylvie Dupret, Marc Antoine Noels, Arlette Ferguson, Jason W.
Théado, Sylvie
Dupret, Marc Antoine
Noels, Arlette
Ferguson, Jason W.
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2008-11-06
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Article
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Keywords
Diffusion,Stars: Abundances,Stars: Chemically Peculiar,Stars: Evolution,Stars: Interiors,Sun: Oscillations,Chemical Elements,Motion Estimation,Stars: Abundances,Stars: Chemically Peculiar,Stars: Evolution,Stars: Interiors,Sun: Oscillations,Stars
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New light on the driving mechanism in roAp stars - I. Effects of metallicity S. Théado, M.-A. Dupret, A. Noels and J. W. Ferguson A&A, 493 1 (2009) 159-174 DOI: https://doi.org/10.1051/0004-6361:200810494
Abstract
Context. Observations suggest that a relationship exists between the driving mechanism of roAp star pulsations and the heavy element distribution in these stars.Aims. We attempt to study the effects of local and global metallicity variations on the excitation mechanism of high order p-modes in A star models.Methods. We developed stellar evolutionary models to describe magnetic A stars with different global metallicity or local metal accumulation profiles. These models were computed with CLES ("Code Liègeois d'évolution stellaire"), and the stability of our models was assessed with the non-adiabatic oscillation code MAD.Results. Our models reproduce the blue edge of the roAp star instability strip, but generate a red edge hotter than the observed one, regardless of metallicity. Surprisingly, we find that an increase in opacity inside the driving region can produce a lower amount of driving, which we refer to as the "inverse k-mechanism". © 2008 ESO. © 2009 Elsevier B.V., All rights reserved.
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This is an open access article under the CC BY license.
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EDP Sciences
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Astronomy and Astrophysics
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0004-6361
1432-0746
1432-0746