SHULYAK, Denis, Jiří KRTIČKA, Zdeněk MIKULÁŠEK, Oleg KOCHUKHOV and Theresa LÜFTINGER. Modelling the light variability of the Ap star epsilon Ursae Majoris. Astronomy and Astrophysics. Les Ulis Cedex, France: EDP Sciences, 2010, vol. 524, November, p. A66-1;A66-9, 9 pp. ISSN 0004-6361.
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Basic information
Original name Modelling the light variability of the Ap star epsilon Ursae Majoris
Name in Czech Modelování světelné proměnnosti Ap hvězdy epsilon UMa
Name (in English) Modelling the light variability of the Ap star epsilon Ursae Majoris
Authors SHULYAK, Denis (804 Ukraine), Jiří KRTIČKA (203 Czech Republic, guarantor, belonging to the institution), Zdeněk MIKULÁŠEK (203 Czech Republic, belonging to the institution), Oleg KOCHUKHOV (804 Ukraine) and Theresa LÜFTINGER (40 Austria).
Edition Astronomy and Astrophysics, Les Ulis Cedex, France, EDP Sciences, 2010, 0004-6361.
Other information
Original language Czech
Type of outcome Article in a journal
Field of Study 10308 Astronomy
Country of publisher France
Confidentiality degree is not subject to a state or trade secret
WWW URL
Impact factor Impact factor: 4.425
RIV identification code RIV/00216224:14310/10:00040632
Organization unit Faculty of Science
UT WoS 000284625300056
Keywords (in Czech) hvězdy: chemicky pekuliární; hvězdy: proměnné: hvězdy: atmosféry; hvězdy: jednotlivé: epsilon UMa
Keywords in English stars: chemically peculiar; stars: variables: general; stars: atmospheres; stars: individual: epsilon UMa
Tags International impact, Reviewed
Changed by Changed by: prof. Mgr. Jiří Krtička, Ph.D., učo 8714. Changed: 10/2/2011 17:30.
Abstract
Aims. We simulate the light variability of the Ap star epsilon UMa using the observed surface distributions of Fe, Cr, Ca, Mn, Mg, Sr, and Ti obtained with the help of the Doppler imaging technique. Methods. Using all photometric data available, we specified light variations of epsilon UMa modulated by its rotation from far UV to IR. We employed the LLmodels stellar model atmosphere code to predict the light variability in different photometric systems. Results. The rotational period of epsilon UMa is refined to 5.088631(18) day. It is shown that the observed light variability can be explained as a result of the redistribution of radiative flux from the UV spectral region to the visual caused by the inhomogeneous surface distribution of chemical elements. Among seven mapped elements, only Fe and Cr contribute significantly to the amplitude of the observed light variability. In general, we find very good agreement between theory and observations. We confirm the important role of Fe and Cr in determining the magnitude of the well-known depression around 5200 A by analyzing the peculiar a-parameter. Finally, we show that the abundance spots of considered elements cannot explain the observed variabilities in near UV and beta index, which probably have other causes. Conclusions. The inhomogeneous surface distribution of chemical elements can explain most of the observed light variability of the A-type CP star epsilon UMa.
Abstract (in English)
Aims. We simulate the light variability of the Ap star epsilon UMa using the observed surface distributions of Fe, Cr, Ca, Mn, Mg, Sr, and Ti obtained with the help of the Doppler imaging technique. Methods. Using all photometric data available, we specified light variations of epsilon UMa modulated by its rotation from far UV to IR. We employed the LLmodels stellar model atmosphere code to predict the light variability in different photometric systems. Results. The rotational period of epsilon UMa is refined to 5.088631(18). It is shown that the observed light variability can be explained as a result of the redistribution of radiative flux from the UV spectral region to the visual caused by the inhomogeneous surface distribution of chemical elements. Among seven mapped elements, only Fe and Cr contribute significantly to the amplitude of the observed light variability. In general, we find very good agreement between theory and observations. We confirm the important role of Fe and Cr in determining the magnitude of the well-known depression around 5200 A by analyzing the peculiar a-parameter. Finally, we show that the abundance spots of considered elements cannot explain the observed variabilities in near UV and beta index, which probably have other causes. Conclusions. The inhomogeneous surface distribution of chemical elements can explain most of the observed light variability of the A-type CP star epsilon UMa.
Links
IAA301630901, research and development projectName: Rozložení energie ve spektru horkých hvězd a jeho proměnnost
Investor: Academy of Sciences of the Czech Republic, Spectral energy distribution of hot stars and its variability
MEB061014, research and development projectName: Magnetické a proměnné hvězdy: od pozemských pozorování k družicovým
Investor: Ministry of Education, Youth and Sports of the CR, Programme KONTAKT - mobilities (MEB)
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