Ultraviolet and visual flux and line variations of one of the
least variable Bp stars HD 64740

J 2013

Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740

KRTIČKA, Jiří, Jan JANÍK, Hana MARKOVÁ, Zdeněk MIKULÁŠEK, Juraj ZVERKO et. al.

Základní údaje

Originální název

Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740

Autoři

KRTIČKA, Jiří (203 Česká republika, garant, domácí), Jan JANÍK (203 Česká republika, domácí), Hana MARKOVÁ (203 Česká republika, domácí), Zdeněk MIKULÁŠEK (203 Česká republika, domácí), Juraj ZVERKO (703 Slovensko), Milan PRVÁK (203 Česká republika, domácí) a Marek SKARKA (203 Česká republika, domácí)

Vydání

Astronomy and Astrophysics, Les Ulis Cedex, France, EDP Sciences, 2013, 0004-6361

Další údaje

Jazyk

angličtina

Typ výsledku

Článek v odborném periodiku

Obor

10308 Astronomy

Stát vydavatele

Francie

Utajení

není předmětem státního či obchodního tajemství

Odkazy

URL

Impakt faktor

Impact factor: 4.479

Kód RIV

RIV/00216224:14310/13:00066262

Organizační jednotka

Přírodovědecká fakulta

DOI

http://dx.doi.org/10.1051/0004-6361/201221018

UT WoS

000323893500018

Klíčová slova anglicky

stars: chemically peculiar; stars: early-type; stars: variables: general; stars: winds; outflows; ultraviolet: stars; stars: individual: HD 64740

Štítky

AKR, rivok

Příznaky

Mezinárodní význam, Recenzováno

Změněno: 18. 6. 2014 11:20, Mgr. Marek Skarka, Ph.D.

Anotace

ORIG CZ

V originále

The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant rotational light variability, while others do not. Aims: We study the Bp star HD 64740 to investigate how its remarkable inhomogeneities in the surface distribution of helium and silicon, and the corresponding strong variability of many spectral lines, can result in one of the faintest photometric variabilities among the Bp stars. Methods: We used model atmospheres and synthetic spectra calculated for the silicon and helium abundances from surface abundance maps to predict the ultraviolet and visual light and line variability of HD 64740. The predicted fluxes and line profiles were compared with the observed ones derived with the IUE, HST, and Hipparcos satellites and with spectra acquired using the FEROS spectrograph at the 2.2 m MPG/ESO telescope in La Silla. Results: We are able to reproduce the observed visual light curve of HD 64740 assuming an inhomogeneous distribution of iron correlated with silicon distribution. The light variations in the ultraviolet are hardly detectable. We detect the variability of many ultraviolet lines of carbon, silicon, and aluminium and discuss the origin of these lines and the nature of their variations. Conclusions: The maximum abundances of helium and silicon on the surface of HD 64740 are not high enough to cause significant light variations. The detected variability of many ultraviolet lines is most likely of atmospheric origin and reflects the inhomogeneous elemental surface distribution. The variability of the C iv resonance lines of carbon is stronger and it probably results from the dependence of the wind mass-loss rate on the chemical composition and magnetic field orientation. We have not been able to detect a clear signature of the matter trapped in the circumstellar clouds.

Česky

Studujeme hvězdu HD 64740 abychom pochopili, proč tato hvězda s nápadnou spektroskopickou proměnností má velmi malou fotometrickou proměnnost. Pro tento účel počítáme modely atmosfér a výstupní spektra a porovnáváme získané výsledky s pozorováními získanými pomocí družic IUE, HST a Hipparcos a pomocí spektrografu FEROS ma 2,2 m dalekohledu ESO/MPG. Jsme schopni vysvětlit pozorovanou ultrafialovou a optickou proměnnost. Maximální obsah křemíku a helia na povrchu této hvězdy není dostatečný na to, aby způsobil výraznější fotometrickou proměnnost.

Návaznosti

GAP209/12/0217, projekt VaV

Název: Multispektrální proměnnost horkých hvězd a její příčiny

Investor: Grantová agentura ČR, Multispektrální proměnnost horkých hvězd a její příčiny

Citovat

KRTIČKA, Jiří, Jan JANÍK, Hana MARKOVÁ, Zdeněk MIKULÁŠEK, Juraj ZVERKO, Milan PRVÁK a Marek SKARKA. Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740. Astronomy and Astrophysics. Les Ulis Cedex, France: EDP Sciences, 2013, roč. 556, léto, s. "A18-1"-"A18-11", 11 s. ISSN 0004-6361. Dostupné z: https://dx.doi.org/10.1051/0004-6361/201221018.

@article{1117824,
   author = {Krtička, Jiří and Janík, Jan and Marková, Hana and Mikulášek, Zdeněk and Zverko, Juraj and Prvák, Milan and Skarka, Marek},
   article_location = {Les Ulis Cedex, France},
   article_number = {léto},
   doi = {http://dx.doi.org/10.1051/0004-6361/201221018},
   keywords = {stars: chemically peculiar; stars: early-type; stars: variables: general; stars: winds; outflows; ultraviolet: stars; stars: individual: HD 64740},
   language = {eng},
   issn = {0004-6361},
   journal = {Astronomy and Astrophysics},
   title = {Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740},
   url = {http://adsabs.harvard.edu/abs/2013A%26A...556A..18K},
   volume = {556},
   year = {2013}
}

TY  - JOUR
ID  - 1117824
AU  - Krtička, Jiří - Janík, Jan - Marková, Hana - Mikulášek, Zdeněk - Zverko, Juraj - Prvák, Milan - Skarka, Marek
PY  - 2013
TI  - Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740
JF  - Astronomy and Astrophysics
VL  - 556
IS  - léto
SP  - "A18-1"-"A18-11"
EP  - "A18-1"-"A18-11"
PB  - EDP Sciences
SN  - 00046361
KW  - stars: chemically peculiar
KW  - stars: early-type
KW  - stars: variables: general
KW  - stars: winds
KW  - outflows
KW  - ultraviolet: stars
KW  - stars: individual: HD 64740
UR  - http://adsabs.harvard.edu/abs/2013A%26A...556A..18K
N2  - The light variability of hot magnetic chemically peculiar stars is typically caused by the flux redistribution in spots with peculiar abundance. This raises the question why some stars with surface abundance spots show significant rotational light variability, while others do not. Aims: We study the Bp star HD 64740 to investigate how its remarkable inhomogeneities in the surface distribution of helium and silicon, and the corresponding strong variability of many spectral lines, can result in one of the faintest photometric variabilities among the Bp stars. Methods: We used model atmospheres and synthetic spectra calculated for the silicon and helium abundances from surface abundance maps to predict the ultraviolet and visual light and line variability of HD 64740. The predicted fluxes and line profiles were compared with the observed ones derived with the IUE, HST, and Hipparcos satellites and with spectra acquired using the FEROS spectrograph at the 2.2 m MPG/ESO telescope in La Silla. Results: We are able to reproduce the observed visual light curve of HD 64740 assuming an inhomogeneous distribution of iron correlated with silicon distribution. The light variations in the ultraviolet are hardly detectable. We detect the variability of many ultraviolet lines of carbon, silicon, and aluminium and discuss the origin of these lines and the nature of their variations. Conclusions: The maximum abundances of helium and silicon on the surface of HD 64740 are not high enough to cause significant light variations. The detected variability of many ultraviolet lines is most likely of atmospheric origin and reflects the inhomogeneous elemental surface distribution. The variability of the C iv resonance lines of carbon is stronger and it probably results from the dependence of the wind mass-loss rate on the chemical composition and magnetic field orientation. We have not been able to detect a clear signature of the matter trapped in the circumstellar clouds.
ER  -

KRTIČKA, Jiří, Jan JANÍK, Hana MARKOVÁ, Zdeněk MIKULÁŠEK, Juraj ZVERKO, Milan PRVÁK a Marek SKARKA. Ultraviolet and visual flux and line variations of one of the least variable Bp stars HD 64740. \textit{Astronomy and Astrophysics}. Les Ulis Cedex, France: EDP Sciences, 2013, roč.~556, léto, s.~''A18-1''-''A18-11'', 11 s. ISSN~0004-6361. Dostupné z: https://dx.doi.org/10.1051/0004-6361/201221018.

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