Modeling variability of Be stars

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F19%3A00107398" target="_blank" >RIV/00216224:14310/19:00107398 - isvavai.cz</a>

Výsledek na webu

<a href="http://var.astro.cz/oejv/issues/oejv0197.pdf" target="_blank" >http://var.astro.cz/oejv/issues/oejv0197.pdf</a>

DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Modeling variability of Be stars

Popis výsledku v původním jazyce

Be stars are rapidly rotating non-supergiant B-type stars surrounded by equatorial Keplerian disks. The characteristic property of all Be stars is their multiperiodic variability driven for example by pulsations in isolated Be stars or by the effects of binarity. We assume in our models the equatorial decretion disk that stems from the angular momentum loss needed to keep the central object at or below the critical rotation. Using our hydrodynamic code, we calculate the 2D profile of Be stars’ disk structure under various physical and geometrical configurations of the star-disk system as well as various profiles of the circumstellar medium. The tidal interactions in binary systems facilitate the matter ejection from the equatorial region of the star, and there is also evidence of warping of the disk in binaries. The important subclass is the Be/X-ray binaries, consisting of a Be star and mostly a neutron star (NS), which belong to the brightest objects in the X-ray sky. Intensive matter accretion from the optical donor companion onto the compact object in a relatively close binary system produces transient phases of the high energy X-ray emission which dramatically vary in brightness and whose timescales may range from milliseconds to years. We calculate the effects of X-ray irradiation on the temperature structure of the Be stars’ disk. Using the Bondi-Hoyle-Littleton approximation, we estimate the NS accretion rate and the excess of X-ray luminosity during various phases of NS-disk interaction.

Název v anglickém jazyce

Modeling variability of Be stars

Popis výsledku anglicky

Be stars are rapidly rotating non-supergiant B-type stars surrounded by equatorial Keplerian disks. The characteristic property of all Be stars is their multiperiodic variability driven for example by pulsations in isolated Be stars or by the effects of binarity. We assume in our models the equatorial decretion disk that stems from the angular momentum loss needed to keep the central object at or below the critical rotation. Using our hydrodynamic code, we calculate the 2D profile of Be stars’ disk structure under various physical and geometrical configurations of the star-disk system as well as various profiles of the circumstellar medium. The tidal interactions in binary systems facilitate the matter ejection from the equatorial region of the star, and there is also evidence of warping of the disk in binaries. The important subclass is the Be/X-ray binaries, consisting of a Be star and mostly a neutron star (NS), which belong to the brightest objects in the X-ray sky. Intensive matter accretion from the optical donor companion onto the compact object in a relatively close binary system produces transient phases of the high energy X-ray emission which dramatically vary in brightness and whose timescales may range from milliseconds to years. We calculate the effects of X-ray irradiation on the temperature structure of the Be stars’ disk. Using the Bondi-Hoyle-Littleton approximation, we estimate the NS accretion rate and the excess of X-ray luminosity during various phases of NS-disk interaction.

Druh

D - Stať ve sborníku

CEP obor

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OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

Proceedings of the 50thConference on Variable Stars Research

ISBN

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ISSN

1801-5964

e-ISSN

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Počet stran výsledku

7

Strana od-do

43-49

Název nakladatele

Open European Journal on Variable Stars

Místo vydání

Neuveden

Místo konání akce

Brno

Datum konání akce

30. 11. 2018

Typ akce podle státní příslušnosti

EUR - Evropská akce

Kód UT WoS článku

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