The mechanism of the light variability of chemically peculiar stars

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Authors

KRTIČKA Jiří MIKULÁŠEK Zdeněk ZVERKO Juraj ŽIŽŇOVSKÝ Jozef HENRY Gregory SKALICKÝ Jan ZVĚŘINA Pavel

Year of publication 2010
Type Article in Proceedings
Conference Solar and Stellar Variability: Impact on Earth and Planets, IAUS 264
MU Faculty or unit

Faculty of Science

Citation
Web http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=7277352
Doi http://dx.doi.org/10.1017/S1743921309992754
Field Astronomy and astrophysics
Keywords stars: atmospheres; stars: chemically peculiar; stars: spots; stars: variables: other
Description Until recently, the mechanism of the light variability of chemically peculiar (CP) stars was unclear. To improve this situation, we started a theoretical and observational campaign aimed at the nature of the light variability of these stars. We use the TLUSTY model atmospheres calculated for the appropriate surface chemical composition to obtain the emergent flux and to predict the rotationally modulated light curves. We show on example of several well-studied CP stars that their light variations can be explained as a result of i) the uneven surface distribution of the elements (creating overabundant regions), ii) the flux redistribution from the ultraviolet to the visible part of the spectrum (in the overabundant regions), and iii) rotation of the star. We show that the silicon and helium bound-free transitions and iron bound-bound transitions provide the main contribution to the flux redistribution. This result is also a very precise test of modern stellar model atmospheres. We conclude that the mentioned mechanism is a very promising explanation for the light variations in CP stars of earlier spectral types.
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