Modelling of the ultraviolet and visual SED variability in the
hot magnetic Ap star CU Virginis

J 2012

Modelling of the ultraviolet and visual SED variability in the hot magnetic Ap star CU Virginis

KRTIČKA, Jiří, Zdeněk MIKULÁŠEK, Theresa LÜFTINGER, Denis SHULYAK, Juraj ZVERKO et. al.

Basic information

Original name

Modelling of the ultraviolet and visual SED variability in the hot magnetic Ap star CU Virginis

Name in Czech

Modelování ultrafialové a vizuální proměnnosti magnetické Ap hvězdy CU Virginis

Authors

KRTIČKA, Jiří (203 Czech Republic, guarantor, belonging to the institution), Zdeněk MIKULÁŠEK (203 Czech Republic, belonging to the institution), Theresa LÜFTINGER (40 Austria), Denis SHULYAK (804 Ukraine), Juraj ZVERKO (703 Slovakia), Jozef ŽIŽŇOVSKÝ (703 Slovakia) and Nikolaj SOKOLOV (643 Russian Federation)

Edition

Astronomy and Astrophysics, Les Ulis Cedex, France, EDP Sciences, 2012, 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

References:

URL

Impact factor

Impact factor: 5.084

RIV identification code

RIV/00216224:14310/12:00057077

Organization unit

Faculty of Science

DOI

http://dx.doi.org/10.1051/0004-6361/201117490

UT WoS

000300416800014

Keywords (in Czech)

hvězdy: atmosféry; hvězdy: chemicky pekuliární; hvězdy: skvrny; hvězdy: proměnné

Keywords in English

stars: chemically peculiar; stars: early type; stars; atmospheres; stars: variables: general; stars: individual CU Virginis

Abstract

ORIG CZ

V originále

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.

In Czech

Ukázali jsme, že proměnnost hvězdy CU Vir ve vby filtrech Stromgrenova fotometrického systému je výsledkem nerovnoměrného rozložení křemíku, chrómu a železa na povrchu této hvězdy, přerozdělení toku z ultrafialové do viditelné oblasti a hvězdné rotace. Poměrně dobře jsme také předpověděli ultrafialový tok a jeho proměnnost. Proměnnost pozorovaná ve viditelné oblasti je jen slabým odleskem ultrafialové proměnnosti.

Links

IAA301630901, research and development project

Name: 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 project

Name: Magnetické a proměnné hvězdy: od pozemských pozorování k družicovým

Investor: Ministry of Education, Youth and Sports of the CR, Programme KONTAKT - mobilities (MEB)

Citovat

KRTIČKA, Jiří, Zdeněk MIKULÁŠEK, Theresa LÜFTINGER, Denis SHULYAK, Juraj ZVERKO, Jozef ŽIŽŇOVSKÝ and Nikolaj SOKOLOV. Modelling of the ultraviolet and visual SED variability in the hot magnetic Ap star CU Virginis. Astronomy and Astrophysics. Les Ulis Cedex, France: EDP Sciences, 2012, vol. 537, A14, p. A14-1;A11-14, 14 pp. ISSN 0004-6361. Available from: https://dx.doi.org/10.1051/0004-6361/201117490.

@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 and 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, 2012, vol.~537, A14, p.~A14-1;A11-14, 14 pp. ISSN~0004-6361. Available from: https://dx.doi.org/10.1051/0004-6361/201117490.

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