| KRTIČKA, Jiří, Jan JANÍK, Iva KRTIČKOVÁ, S. MEREGHETTI, F. PINTORE, P. NEMETH, Jiří KUBÁT a M. VUCKOVIC. Hot subdwarf wind models with accurate abundances I. Hydrogen dominated stars HD 49798 and BD+18 degrees 2647. ASTRONOMY & ASTROPHYSICS. LES ULIS CEDEX A: EDP SCIENCES S A, 2019, roč. 631, OCT 22 2019, s. 1-11. ISSN 0004-6361. Dostupné z: https://dx.doi.org/10.1051/0004-6361/201936208. |
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@article{1640720,
author = {Krtička, Jiří and Janík, Jan and Krtičková, Iva and Mereghetti, S. and Pintore, F. and Nemeth, P. and Kubát, Jiří and Vuckovic, M.},
article_location = {LES ULIS CEDEX A},
article_number = {OCT 22 2019},
doi = {http://dx.doi.org/10.1051/0004-6361/201936208},
keywords = {stars: winds; outflows stars; mass-loss; stars: early-type; subdwarfs; X-rays: binaries},
language = {eng},
issn = {0004-6361},
journal = {ASTRONOMY & ASTROPHYSICS},
title = {Hot subdwarf wind models with accurate abundances I. Hydrogen dominated stars HD 49798 and BD+18 degrees 2647},
url = {http://dx.doi.org/10.1051/0004-6361/201936208},
volume = {631},
year = {2019}
}
TY - JOUR
ID - 1640720
AU - Krtička, Jiří - Janík, Jan - Krtičková, Iva - Mereghetti, S. - Pintore, F. - Nemeth, P. - Kubát, Jiří - Vuckovic, M.
PY - 2019
TI - Hot subdwarf wind models with accurate abundances I. Hydrogen dominated stars HD 49798 and BD+18 degrees 2647
JF - ASTRONOMY & ASTROPHYSICS
VL - 631
IS - OCT 22 2019
SP - 1-11
EP - 1-11
PB - EDP SCIENCES S A
SN - 00046361
KW - stars: winds
KW - outflows stars
KW - mass-loss
KW - stars: early-type
KW - subdwarfs
KW - X-rays: binaries
UR - http://dx.doi.org/10.1051/0004-6361/201936208
L2 - http://dx.doi.org/10.1051/0004-6361/201936208
N2 - 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.
ER -
KRTIČKA, Jiří, Jan JANÍK, Iva KRTIČKOVÁ, S. MEREGHETTI, F. PINTORE, P. NEMETH, Jiří KUBÁT a M. VUCKOVIC. Hot subdwarf wind models with accurate abundances I. Hydrogen dominated stars HD 49798 and BD+18 degrees 2647. \textit{ASTRONOMY \&{} ASTROPHYSICS}. LES ULIS CEDEX A: EDP SCIENCES S A, 2019, roč.~631, OCT 22 2019, s.~1-11. ISSN~0004-6361. Dostupné z: https://dx.doi.org/10.1051/0004-6361/201936208.
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