Modelling the light variability of the Ap star epsilon Ursae Majoris

SHULYAK, Denis, Jiří KRTIČKA, Zdeněk MIKULÁŠEK, Oleg KOCHUKHOV a Theresa LÜFTINGER. Modelling the light variability of the Ap star epsilon Ursae Majoris. Astronomy and Astrophysics. Les Ulis Cedex, France: EDP Sciences, 2010, roč. 524, November, s. A66-1;A66-9, 9 s. ISSN 0004-6361.

Základní údaje

• Originální název: Modelling the light variability of the Ap star epsilon Ursae Majoris
• Název česky: Modelování světelné proměnnosti Ap hvězdy epsilon UMa
• Název anglicky: Modelling the light variability of the Ap star epsilon Ursae Majoris
• Autoři: SHULYAK, Denis (804 Ukrajina), Jiří KRTIČKA (203 Česká republika, garant, domácí), Zdeněk MIKULÁŠEK (203 Česká republika, domácí), Oleg KOCHUKHOV (804 Ukrajina) a Theresa LÜFTINGER (40 Rakousko).
• Vydání: Astronomy and Astrophysics, Les Ulis Cedex, France, EDP Sciences, 2010, 0004-6361.

Další údaje

• Originální jazyk: čeština
• Typ výsledku: Článek v odborném periodiku
• Obor: 10308 Astronomy
• Stát vydavatele: Francie
• Utajení: není předmětem státního či obchodního tajemství
• WWW: URL
• Impakt faktor: Impact factor: 4.425
• Kód RIV: RIV/00216224:14310/10:00040632
• Organizační jednotka: Přírodovědecká fakulta
• UT WoS: 000284625300056
• Klíčová slova česky: hvězdy: chemicky pekuliární; hvězdy: proměnné: hvězdy: atmosféry; hvězdy: jednotlivé: epsilon UMa
• Klíčová slova anglicky: stars: chemically peculiar; stars: variables: general; stars: atmospheres; stars: individual: epsilon UMa
• Příznaky: Mezinárodní význam, Recenzováno

Anotace

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.

Anotace anglicky

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.

Návaznosti

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Investor: Akademie věd ČR, Rozložení energie ve spektru horkých hvězd a jeho proměnnost

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