Nonradial Modes in RR Lyr Stars

• Autorzy: Dziembowski W. A. , Cassisi S.
• Języki publikacji: EN

Abstrakty

EN

We present a survey of nonradial mode properties in evolutionary sequences of RR Lyr 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 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 Lyr stars.

Słowa kluczowe

EN

stars: oscillations; stars: interiors

• Wydawca: Copernicus Foundation for Polish Astronomy
• Czasopismo: Acta Astronomica
• Rocznik: 1999
• Tom: Vol. 49, No. 3
• Strony: 371--382
• Opis fizyczny: Bibliogr. 17 poz., wykr.

Twórcy

autor

Dziembowski W. A.

• Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland

autor

Cassisi S.

• Osservatorio Astronomico Collurania, I-64100, Teramo, Italy

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