Hot subdwarf wind models with accurate abundances I. Hydrogen dominated stars HD 49798 and BD+18 degrees 2647

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216224%3A14310%2F19%3A00108216" target="_blank" >RIV/00216224:14310/19:00108216 - isvavai.cz</a>

Result on the web

<a href="http://dx.doi.org/10.1051/0004-6361/201936208" target="_blank" >http://dx.doi.org/10.1051/0004-6361/201936208</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/201936208" target="_blank" >10.1051/0004-6361/201936208</a>

Result language

angličtina

Original language name

Hot subdwarf wind models with accurate abundances I. Hydrogen dominated stars HD 49798 and BD+18 degrees 2647

Original language description

Context. Hot subdwarfs are helium burning objects in late stages of their evolution. These subluminous stars can develop winds driven by light absorption in the lines of heavier elements. The wind strength depends on chemical composition which can significantly vary from star to star. Aims. We aim to understand the influence of metallicity on the strength of the winds of the hot hydrogen-rich subdwarfs HD 49798 and BD+18 2647. Methods. We used high -resolution UV and optical spectra to derive stellar parameters and abundances using the TLUSTY and SYNSPEC codes. For derived stellar parameters, we predicted wind structure (including mass -loss rates and terminal velocities) with our METUJE code. Results. We derived effective temperature Teff = 45 900 K and mass M = 1.46 M for HD 49798 and Teff = 73 000 K and M = 0.38 M for BD+18 2647. The derived surface abundances can be interpreted as a result of interplay between stellar evolution and diffusion. The subdwarf HD 49798 has a strong wind that does not allow for chemical separation and consequently the star shows solar chemical composition modified by hydrogen burning. On the other hand, we did not find any wind in BD+18 2647 and its abundances are therefore most likely affected by radiative diffusion. Accurate abundances do not lead to a significant modification of wind mass -loss rate for HD 49798, because the increase of the contribution of iron and nickel to the radiative force is compensated by the decrease of the radiative force due to other elements. The resulting wind mass -loss rate M = 2.1 x 10-9 M. yr1 predicts an X-ray light curve during the eclipse which closely agrees with observations. On the other hand, the absence of the wind in BD+18 2647 for accurate abundances is a result of its peculiar chemical composition. Conclusions. Wind models with accurate abundances provide more reliable wind parameters, but the influence of abundances on the wind parameters is limited in many cases.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

<a href="/en/project/GA18-05665S" target="_blank" >GA18-05665S: Mass-loss in evolved massive stars</a><br>

Continuities

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

Publication year

2019

Confidentiality

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

Name of the periodical

ASTRONOMY & ASTROPHYSICS

ISSN

0004-6361

e-ISSN

—

Volume of the periodical

631

Issue of the periodical within the volume

OCT 22 2019

Country of publishing house

FR - FRANCE

Number of pages

11

Pages from-to

1-11

UT code for WoS article

000515090700003

EID of the result in the Scopus database

2-s2.0-85074450217