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The mechanism of the light variability of chemically peculiar stars

Published online by Cambridge University Press:  26 February 2010

J. Krtička ,
Z. Mikulášek ,
J. Zverko ,
J. Žižňovský ,
G. W. Henry ,
J. Skalický  and
P. Zvěřina
J. Krtička
Affiliation:
Institute of Theoretical Physics and Astrophysics, Masaryk University, CZ-611 37 Brno, Czech Republic
Z. Mikulášek
Affiliation:
Institute of Theoretical Physics and Astrophysics, Masaryk University, CZ-611 37 Brno, Czech Republic
J. Zverko
Affiliation:
Astronomical Institute, Slovak Academy of Sciences, SK-059 60 Tatranská Lomnica, Slovakia
J. Žižňovský
Affiliation:
Astronomical Institute, Slovak Academy of Sciences, SK-059 60 Tatranská Lomnica, Slovakia
G. W. Henry
Affiliation:
Center of Excellence in Information Systems, Tennessee State University, Nashville, Tennessee, USA
J. Skalický
Affiliation:
Institute of Theoretical Physics and Astrophysics, Masaryk University, CZ-611 37 Brno, Czech Republic
P. Zvěřina
Affiliation:
Institute of Theoretical Physics and Astrophysics, Masaryk University, CZ-611 37 Brno, Czech Republic
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Abstract

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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.

Keywords

stars: atmospheresstars: chemically peculiarstars: spotsstars: variables: other
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 5 , Symposium S264: Solar and Stellar Variability: Impact on Earth and Planets , August 2009 , pp. 270 - 272
Copyright
Copyright © International Astronomical Union 2010

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