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Hot subdwarf wind models with accurate abundances II. Helium-dominated merger products CD-46 8926 and CD-51 11879
Indexado
WoS WOS:001181364400009
Scopus SCOPUS_ID:85187234163
DOI 10.1051/0004-6361/202347978
Año 2024
Tipo artículo de investigación

Citas Totales

Autores Afiliación Chile

Instituciones Chile

% Participación
Internacional

Autores
Afiliación Extranjera

Instituciones
Extranjeras


Abstract



Context. Helium-dominated subdwarfs are core helium burning stars stripped of their envelope. The nuclear evolution of these stars alters surface abundances. Modified abundances impact the strength of the stellar wind. Aims. We aim to understand the influence of modified surface abundances on the strength of the stellar wind in the helium-dominated subdwarfs CD-46 8926 and CD-51 11879. A modified wind strength could resolve the problem with the X-ray emission of these stars, as the expected X-ray luminosity of both stars is significantly higher than the upper limit determined from observations. Methods. We used our own optical spectroscopy combined with archival ultraviolet spectroscopy and photometry to derive basic parameters and surface abundances of selected subdwarfs. The resulting parameterst served as input for the METUJE stellar wind code, which predicts the wind structure of these stars. We compared the derived wind parameters with the predictions derived for solar abundances. Results. The optical analysis showed that both subdwarfs have effective temperatures in excess of 60 kK and a strong overabundance of carbon in the case of CD-46 8926 and nitrogen in the case of CD-51 11879. We interpret the abundance patterns as being a result of enrichment by the products of nuclear reactions. The modified abundances reduce the wind mass-loss rate by tens of percent. The reduction improves the predicted wind line profiles in comparison to observations. The change in helium abundance does not have a strong effect on the wind parameters. As a result of a lower estimated bolometric luminosity and mass-loss rate and a larger distance, the expected X-ray luminosities become lower and agree with observational upper limits. Conclusions. The nucleosynthesis does not significantly alter the strength of the wind of hot subdwarfs, but the inclusion of proper stellar parameters improves the agreement with observational wind characteristics. Our analysis indicates that subdwarfs overabundant in helium are typically able to launch wind. This conclusion is supported by data gathered for thousands of subdwarfs from the literature, which shows that subdwarfs overabundant in helium avoid the region in the Kiel diagram where the winds are predicted to be absent. This can be interpreted in terms of the gravitational settling of helium, which is suppressed by the winds.

Revista



Revista ISSN
Astronomy & Astrophysics 0004-6361

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Disciplinas de Investigación



WOS
Astronomy & Astrophysics
Scopus
Sin Disciplinas
SciELO
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Publicaciones WoS (Ediciones: ISSHP, ISTP, AHCI, SSCI, SCI), Scopus, SciELO Chile.

Colaboración Institucional



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Autores - Afiliación



Ord. Autor Género Institución - País
1 Krticka, J. Hombre Masarykova Univ - República Checa
Masaryk University - República Checa
2 Krtickova, I. - Masarykova Univ - República Checa
Masaryk University - República Checa
3 Janik, Jan - Masarykova Univ - República Checa
Masaryk University - República Checa
4 Nemeth, P. Hombre Akad Ceske Republ - República Checa
Astroserver Org - Hungría
Academy of Sciences of the Czech Republic - República Checa
Astroserver.org - Hungría
5 Kubat, J. - Akad Ceske Republ - República Checa
Academy of Sciences of the Czech Republic - República Checa
6 Vuckovic, Maja Mujer Universidad de Valparaíso - Chile

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Financiamiento



Fuente
Ministerio de Economía y Competitividad
Grantová Agentura Ceské Republiky
Spanish MINECO
Ministerstvo Školství, Mládeže a Tělovýchovy
Grant Agency of the Czech Republic
Astronomical Institute Ondejov
e-INFRA CZ project - Ministry of Education, Youth and Sports of the Czech Republic

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Agradecimientos



Agradecimiento
We thank Dr. Sandro Mereghetti for valuable comments on the manuscript and Prof. V. & Scaron;tefl for the discussion of the cool companion. Computational resources were provided by the e-INFRA CZ project (ID:90254), supported by the Ministry of Education, Youth and Sports of the Czech Republic. P.N. acknowledges support from the Grant Agency of the Czech Republic (GA & Ccaron;R 22-34467S). The Astronomical Institute Ondejov is supported by the project RVO:67985815. This publication makes use of VOSA, developed under the Spanish Virtual Observatory project supported from the Spanish MINECO through grant AyA2017-84089.
We thank Dr. Sandro Mereghetti for valuable comments on the manuscript and Prof. V. Štefl for the discussion of the cool companion. Computational resources were provided by the e-INFRA CZ project (ID:90254), supported by the Ministry of Education, Youth and Sports of the Czech Republic. P.N. acknowledges support from the Grant Agency of the Czech Republic (GACR 22-34467S). The Astronomical Institute Ondrejov is supported by the project RVO:67985815. This publication makes use of VOSA, developed under the Spanish Virtual Observatory project supported from the Spanish MINECO through grant AyA2017-84089.
We thank Dr. Sandro Mereghetti for valuable comments on the manuscript and Prof. V. Štefl for the discussion of the cool companion. Computational resources were provided by the e-INFRA CZ project (ID:90254), supported by the Ministry of Education, Youth and Sports of the Czech Republic. P.N. acknowledges support from the Grant Agency of the Czech Republic (GACR 22-34467S). The Astronomical Institute Ondrejov is supported by the project RVO:67985815. This publication makes use of VOSA, developed under the Spanish Virtual Observatory project supported from the Spanish MINECO through grant AyA2017-84089.

Muestra la fuente de financiamiento declarada en la publicación.