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@article{966947,
author = {Krtička, Jiří and Mikulášek, Zdeněk and Lüftinger, Theresa and Shulyak, Denis and Zverko, Juraj and Žižňovský, Jozef and Sokolov, Nikolaj},
article_location = {Les Ulis Cedex, France},
article_number = {A14},
doi = {http://dx.doi.org/10.1051/0004-6361/201117490},
keywords = {stars: chemically peculiar; stars: early type; stars; atmospheres; stars: variables: general; stars: individual CU Virginis},
language = {eng},
issn = {0004-6361},
journal = {Astronomy and Astrophysics},
title = {Modelling of the ultraviolet and visual SED variability in the hot magnetic Ap star CU Virginis},
url = {http://adsabs.harvard.edu/abs/2012A%26A...537A..14K},
volume = {537},
year = {2012}
}
TY - JOUR
ID - 966947
AU - Krtička, Jiří - Mikulášek, Zdeněk - Lüftinger, Theresa - Shulyak, Denis - Zverko, Juraj - Žižňovský, Jozef - Sokolov, Nikolaj
PY - 2012
TI - Modelling of the ultraviolet and visual SED variability in the hot magnetic Ap star CU Virginis
JF - Astronomy and Astrophysics
VL - 537
IS - A14
SP - A14-1;A11-14
EP - A14-1;A11-14
PB - EDP Sciences
SN - 00046361
KW - stars: chemically peculiar
KW - stars: early type
KW - stars
KW - atmospheres
KW - stars: variables: general
KW - stars: individual CU Virginis
UR - http://adsabs.harvard.edu/abs/2012A%26A...537A..14K
L2 - http://adsabs.harvard.edu/abs/2012A%26A...537A..14K
N2 - Context. The spectral energy distribution (SED) in chemically peculiar stars may be significantly affected by their abundance anomalies. The observed SED variations are usually assumed to be a result of inhomogeneous surface distribution of chemical elements, flux redistribution and stellar rotation. However, the direct evidence for this is still only scarce. Aims: We aim to identify the processes that determine the SED and its variability in the UV and visual spectral domains of the helium-weak star CU Vir. Methods: We used the TLUSTY model atmospheres calculated for the appropriate surface chemical composition to obtain the emergent flux and predict the rotationally modulated flux variability of the star. Results: We show that most of the light variations in the vby filters of the Strömgren photometric system are a result of the uneven surface distribution of silicon, chromium, and iron. Our models are only able to explain a part of the variability in the u filter, however. The observed UV flux distribution is very well reproduced, and the models are able to explain most of the observed features in the UV light curve, except for the region 2000-2500 A, where the amplitude of the observed light variations is higher than predicted. The variability observed in the visible is merely a faint gleam of that in the UV. While the amplitude of the light curves reaches only several hundredths of magnitude in the visual domain, it reaches about 1 mag in the UV. Conclusions: The visual and UV light variability of CU Vir is caused by the flux redistribution from the far UV to near UV and visible regions, inhomogeneous distribution of the elements and stellar rotation. Bound-free transitions of silicon and bound-bound transitions of iron and chromium contribute the most to the flux redistribution. This mechanism can explain most of the rotationally modulated light variations in the filters centred on the Paschen continuum and on the UV continuum of the star CU Vir.
ER -
KRTIČKA, Jiří, Zdeněk MIKULÁŠEK, Theresa LÜFTINGER, Denis SHULYAK, Juraj ZVERKO, Jozef ŽIŽŇOVSKÝ a Nikolaj SOKOLOV. Modelling of the ultraviolet and visual SED variability in the hot magnetic Ap star CU Virginis. \textit{Astronomy and Astrophysics}. Les Ulis Cedex, France: EDP Sciences, roč.~537, A14, s.~A14-1;A11-14, 14 s. ISSN~0004-6361. doi:10.1051/0004-6361/201117490. 2012.
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