Publication details

The nature of the light variability of the silicon star HR 7224

Authors

KRTIČKA Jiří MIKULÁŠEK Zdeněk HENRY Gregory W. ZVERKO Juraj ZIZNOVSKY Jozef SKALICKÝ Jan ZVĚŘINA Pavel

Year of publication 2009
Type Article in Periodical
Magazine / Source Astronomy and Astrophysics
MU Faculty or unit

Faculty of Science

Citation
Web http://www.aanda.org/index.php?option=article&access=doi&doi=10.1051/0004-6361/200811123
Field Astronomy and astrophysics
Keywords stars: chemically peculiar -- stars: early type -- stars: variables: general -- stars: individual: HR 7224
Description Although photometric variations of CP stars are frequently used to determine their rotational periods, the detailed mechanism of their light variability remains poorly understood. We simulate the light variability of HR 7224 using the observed surface distribution of Si and Fe. We calculated for the appropriate Si and Fe abundances to obtain the emergent flux and to predict the rotationally modulated light curve of the star. We also obtained additional photometric measurements. We show that the silicon b-f transitions and iron b-b transitions provide the main contribution to the flux redistribution, although an additional source of opacity is needed. We confirm that numerous iron lines significantly contribute to the well-known depression at 5200 A and discuss the connection between iron abundance and the value of peculiarity index a. The uneven surface distribution of silicon and iron is able to explain most of the rotationally modulated light variation in the star HR 7224.
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