1999/07/29 by W. A. Dziembowski, S. Cassisi, Dziembowski, W. A. +1
Physics and Astronomy · #Astro and Planetary Science #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9907414
submitted to Acta Astronomica, 17 pages, latex file and 8 figures in in separate eps files
arxiv created 1999/07/29 · openalex publication_date 1999/07/29 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a survey of nonradial mode properties in evolutionary sequences of RR Lyrae star models. Attention is focused on the modes that may be driven by the opacity mechanism and on those that may be excited as a consequence of the 1:1 resonance with the radial pulsation. Qualitatively, all the models share the same properties of the nonradial modes. At the quantitative level, the properties are to a large extent determined by the radial mode periods. There is only weak dependence on the star metallicity and no apparent dependence on the evolutionary status, that is on the helium exhaustion in the convective core. In the whole range of RRab and RRc star parameters we find unstable nonradial modes driven by the opacity mechanism. An instability of radial pulsation to a resonant excitation of nonradial oscillations is also a common phenomenon in both types. We discuss a possible role of nonradial modes in amplitude modulation observed in certain RR Lyrae stars.