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Astron. Astrophys. 351, 103-118 (1999)

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A nonlinear convective model of pulsating stars

II. RR Lyrae stars

M.U. Feuchtinger

Institut für Astronomie der Universität Wien, Türkenschanzstrasse 17, 1180 Wien, Austria

Received 11 January 1999 / Accepted 16 September 1999


The Vienna nonlinear convective pulsation code is applied to the case of RR Lyrae stars. Assuming two sets of stellar parameters (M = 0.65 [FORMULA], L = 52.5 [FORMULA], [FORMULA] and M = 0.75 [FORMULA], L = 52.5 [FORMULA], [FORMULA]) we compute fundamental and first overtone limit cycle solutions for effective temperatures ranging from 6000 to 7100 K. The resulting light- and radial velocity curves are compared in detail with corresponding models in the literature and with recent observations.

As main result, the light curve morphology is in good agreement with observed RR Lyrae light curves. In particular the theoretical light curve Fourier parameters up to the fifth order lie almost completely within the observed ranges, which means that we are able to resolve the well known RR Lyrae phase discrepancy problem. Regarding the radial velocity variations deviations from observed Fourier parameters occur. Possible explanations like the calibration of the turbulent convection model or the transformation from theoretical to observed radial velocities are discussed.

Key words: hydrodynamics – methods: numerical – stars: oscillations – stars: variables: RR Lyr

Send offprint requests to: M.U. Feuchtinger (fm@amok.astro.univie.ac.at)

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© European Southern Observatory (ESO) 1999

Online publication: November 2, 1999