Global hot-star wind models for stars from Magellanic Clouds

J 2018

Global hot-star wind models for stars from Magellanic Clouds

KRTIČKA, Jiří a Jiří KUBÁT

Základní údaje

Originální název

Global hot-star wind models for stars from Magellanic Clouds

Název česky

Globální modely větru horkých hvězd z Magellanových mračen

Autoři

KRTIČKA, Jiří (203 Česká republika, garant, domácí) a Jiří KUBÁT (203 Česká republika)

Vydání

Astronomy and Astrophysics, EDP Sciences, 2018, 1432-0746

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: 6.209

Kód RIV

RIV/00216224:14310/18:00100896

Organizační jednotka

Přírodovědecká fakulta

DOI

http://dx.doi.org/10.1051/0004-6361/201731969

UT WoS

000430139600001

Klíčová slova anglicky

stars: winds outflows; stars: mass-loss; stars: early-type; Magellanic Clouds; hydrodynamics; radiative transfer

Příznaky

Mezinárodní význam, Recenzováno

Změněno: 17. 12. 2018 23:44, prof. Mgr. Jiří Krtička, Ph.D.

Anotace

ORIG CZ

V originále

We provide mass-loss rate predictions for O stars from Large and Small Magellanic Clouds. We calculate global (unified, hydrodynamic) model atmospheres of main sequence, giant, and supergiant stars for chemical composition corresponding to Magellanic Clouds. The models solve radiative transfer equation in comoving frame, kinetic equilibrium equations (also known as NLTE equations), and hydrodynamical equations from (quasi-)hydrostatic atmosphere to expanding stellar wind. The models allow us to predict wind density, velocity, and temperature (consequently also the terminal wind velocity and the mass-loss rate) just from basic global stellar parameters. As a result of their lower metallicity, the line radiative driving is weaker leading to lower wind mass-loss rates with respect to the Galactic stars. We provide a formula that fits the mass-loss rate predicted by our models as a function of stellar luminosity and metallicity. On average, the mass-loss rate scales with metallicity as dMdt sim Z^0.59. The predicted mass-loss rates are lower than mass-loss rates derived from Halpha diagnostics and can be reconciled with observational results assuming clumping factor Cc = 9. On the other hand, the predicted mass-loss rates either agree or are slightly higher than the mass-loss rates derived from ultraviolet wind line profiles. The calculated P v ionization fractions also agree with values derived from observations for LMC stars with Teff < 40 000 K. Taken together, our theoretical predictions provide reasonable models with consistent mass-loss rate determination, which can be used for quantitative study of stars from Magellanic Clouds.

Česky

Počítáme rychlost ztráty hvězd typu O z Velkého a Malého Magellanova mračna. Modely předpovídají hustotu, rychlost a teplotu větru. V důsledku menšího obsahu těžších prvků je rychlost ztráty hmoty menší než hvězd z naší Galaxie. Předpovězená rychlost ztráty hmoty souhlasí s hodnotami odvozenými z pozorování síly čáry Halfa za předpokladu, že faktor nehomogenity je roven alespoň 9. Na druhou stranu předpovědi dobře souhlasí s výsledky získanými z ultrafialové oblasti.

Návaznosti

GA13-10589S, projekt VaV

Název: Ztráta hmoty horkých hmotných hvězd

Investor: Grantová agentura ČR, Ztráta hmoty horkých hmotných hvězd

Citovat

KRTIČKA, Jiří a Jiří KUBÁT. Global hot-star wind models for stars from Magellanic Clouds. Astronomy and Astrophysics. EDP Sciences, 2018, roč. 612, duben, s. "A20-1"-"A20-11", 11 s. ISSN 1432-0746. Dostupné z: https://dx.doi.org/10.1051/0004-6361/201731969.

@article{1414058,
   author = {Krtička, Jiří and Kubát, Jiří},
   article_number = {duben},
   doi = {http://dx.doi.org/10.1051/0004-6361/201731969},
   keywords = {stars: winds outflows; stars: mass-loss; stars: early-type; Magellanic Clouds; hydrodynamics; radiative transfer},
   language = {eng},
   issn = {1432-0746},
   journal = {Astronomy and Astrophysics},
   title = {Global hot-star wind models for stars from Magellanic Clouds},
   url = {https://www.aanda.org/articles/aa/abs/2018/04/aa31969-17/aa31969-17.html},
   volume = {612},
   year = {2018}
}

TY  - JOUR
ID  - 1414058
AU  - Krtička, Jiří - Kubát, Jiří
PY  - 2018
TI  - Global hot-star wind models for stars from Magellanic Clouds
JF  - Astronomy and Astrophysics
VL  - 612
IS  - duben
SP  - "A20-1"-"A20-11"
EP  - "A20-1"-"A20-11"
PB  - EDP Sciences
SN  - 14320746
KW  - stars: winds outflows
KW  - stars: mass-loss
KW  - stars: early-type
KW  - Magellanic Clouds
KW  - hydrodynamics
KW  - radiative transfer
UR  - https://www.aanda.org/articles/aa/abs/2018/04/aa31969-17/aa31969-17.html
N2  - We provide mass-loss rate predictions for O stars from Large and Small Magellanic Clouds. We calculate global (unified, hydrodynamic) model atmospheres of main sequence, giant, and supergiant stars for chemical composition corresponding to Magellanic Clouds. The models solve radiative transfer equation in comoving frame, kinetic equilibrium equations (also known as NLTE equations), and hydrodynamical equations from (quasi-)hydrostatic atmosphere to expanding stellar wind. The models allow us to predict wind density, velocity, and temperature (consequently also the terminal wind velocity and the mass-loss rate) just from basic global stellar parameters. As a result of their lower metallicity, the line radiative driving is weaker leading to lower wind mass-loss rates with respect to the Galactic stars. We provide a formula that fits the mass-loss rate predicted by our models as a function of stellar luminosity and metallicity. On average, the mass-loss rate scales with metallicity as dMdt sim Z^0.59. The predicted mass-loss rates are lower than mass-loss rates derived from Halpha diagnostics and can be reconciled with observational results assuming clumping factor Cc = 9. On the other hand, the predicted mass-loss rates either agree or are slightly higher than the mass-loss rates derived from ultraviolet wind line profiles. The calculated P v ionization fractions also agree with values derived from observations for LMC stars with Teff < 40 000 K. Taken together, our theoretical predictions provide reasonable models with consistent mass-loss rate determination, which can be used for quantitative study of stars from Magellanic Clouds.
ER  -

KRTIČKA, Jiří a Jiří KUBÁT. Global hot-star wind models for stars from Magellanic Clouds. \textit{Astronomy and Astrophysics}. EDP Sciences, 2018, roč.~612, duben, s.~''A20-1''-''A20-11'', 11 s. ISSN~1432-0746. Dostupné z: https://dx.doi.org/10.1051/0004-6361/201731969.

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