Detailed Information on Publication Record
2015
Visual and ultraviolet flux variability of the bright CP star theta Aurigae
KRTIČKA, Jiří, Zdeněk MIKULÁŠEK, Theresa LUFTINGER and Miroslav JAGELKABasic information
Original name
Visual and ultraviolet flux variability of the bright CP star theta Aurigae
Name in Czech
Vizuální a ultrafialová proměnnost hasné CP hvězdy theta Aurigae
Authors
KRTIČKA, Jiří (203 Czech Republic, guarantor, belonging to the institution), Zdeněk MIKULÁŠEK (203 Czech Republic, belonging to the institution), Theresa LUFTINGER (40 Austria) and Miroslav JAGELKA (703 Slovakia, belonging to the institution)
Edition
ASTRONOMY & ASTROPHYSICS, LES ULIS CEDEX A, EDP SCIENCES S A, 2015, 0004-6361
Other information
Language
English
Type of outcome
Článek v odborném periodiku
Field of Study
10308 Astronomy
Country of publisher
France
Confidentiality degree
není předmětem státního či obchodního tajemství
Impact factor
Impact factor: 4.378 in 2014
RIV identification code
RIV/00216224:14310/15:00081641
Organization unit
Faculty of Science
UT WoS
000357274600017
Keywords in English
stars: chemically peculiar; stars: early-type; stars: variables: general; stars: individual: theta Aurigae
Tags
International impact, Reviewed
Změněno: 14/4/2016 15:38, Ing. Andrea Mikešková
Abstract
V originále
Context. Chemically peculiar stars of the upper part of the main sequence show periodical variability in line intensities and continua, modulated by the stellar rotation, which is attributed to the existence of chemical spots on the surface of these stars. The flux variability is caused by the changing redistribution rate of the radiative flux predominantly from the short-wavelength part of the spectra to the long-wavelength part, which is a result of abundance anomalies. Many details of this process are still unknown. Aims. We study the nature of the multi-spectral variability of one of the brightest chemically peculiar stars, theta Aur. Methods. We predict the flux variability of theta Aur from the emerging intensities calculated for individual surface elements of the star taking into account horizontal variation of chemical composition. The surface chemical composition was derived from Doppler abundance maps. Results. The simulated optical variability in the Stromgren photometric system and the ultraviolet flux variability agree well with observations. The IUE flux distribution is reproduced in great detail by our models in the near ultraviolet region. A minor disagreement remains between the observed and predicted fluxes in the far ultraviolet region. The resonance lines of magnesium and possibly also some lines of silicon are relatively weak in the ultraviolet domain, which indicates non-negligible vertical abundance gradients in the atmosphere. We also derive a new period of the star, P = 3.618 664(10) d, from all available photometric and magnetic measurements and show that the observed rotational period is constant over decades. Conclusions. The ultraviolet and visual variability of theta Aur is mostly caused by silicon bound-free absorption and chromium and iron line absorption. Manganese also contributes to the variability, but to a lesser extent. These elements redistribute the flux mainly from the far-ultraviolet region to the near-ultraviolet and optical regions in the surface abundance spots. The light variability is modulated by the stellar rotation. The ultraviolet domain is key for understanding the properties of chemically peculiar stars. It provides a detailed test for surface abundance models and comprises many lines that originate from states with a low excitation potential, which enable detecting vertical abundance gradients.
Links
| GAP209/12/0217, research and development project |
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| 7AMB14AT015, research and development project |
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