EDP Sciences
Free access
Volume 385, Number 3, April III 2002
Page(s) 932 - 939
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20020182

A&A 385, 932-939 (2002)
DOI: 10.1051/0004-6361:20020182

Nonlinear beat Cepheid and RR Lyrae models

Z. Kolláth1, J. R. Buchler2, R. Szabó1 and Z. Csubry1

1  Konkoly Observatory, Budapest, Hungary
2  Physics Department, University of Florida, Gainesville, FL 32611, USA
    e-mail: buchler@phys.ufl.edu

(Received 3 October 2001 / Accepted 28 January 2002 )

The numerical hydrodynamic modelling of beat Cepheid behavior has been a long-standing quest in which purely radiative models have failed consistently. We find that beat pulsations occur quite naturally when turbulent convection is accounted for in our hydrodynamics code. The developments of a relaxation code and of a Floquet stability analysis greatly facilitate the search for and the analysis of beat Cepheid models. The conditions for the occurrence of beat behavior can be understood easily and at a fundamental level with the help of amplitude equations.

Key words: stars: oscillations -- stars: variables: Cepheids -- stars: variables: RR Lyr -- stars: evolution -- hydrodynamics -- convection

Offprint request: Z. Kolláth, kollath@konkoly.hu

© ESO 2002