New binaries among UV-selected, hot subdwarf stars and population properties
Article
Article Title | New binaries among UV-selected, hot subdwarf stars and population properties |
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ERA Journal ID | 1074 |
Article Category | Article |
Authors | Kawka, A. (Author), Vennes, S. (Author), O'Toole, S. (Author), Nemeth, P. (Author), Burton, D. (Author), Kotze, E. (Author) and Buckle, D. A . H. (Author) |
Journal Title | Monthly Notices of the Royal Astronomical Society |
Journal Citation | 450 (4), pp. 3514-3548 |
Number of Pages | 35 |
Year | 2015 |
Publisher | Oxford University Press |
Place of Publication | United Kingdom |
ISSN | 0035-8711 |
1365-2966 | |
Digital Object Identifier (DOI) | https://doi.org/10.1093/mnras/stv821 |
Web Address (URL) | https://academic.oup.com/mnras/article/450/4/3514/991666 |
Abstract | We have measured the orbital parameters of seven close binaries, including six new objects, in a radial velocity survey of 38 objects comprising a hot subdwarf star with orbital periods ranging from ~0.17 to 3 d. One new system, GALEX J2205-3141, shows reflection on an M dwarf companion. Three other objects show significant short-period variations, but their orbital parameters could not be constrained. Two systems comprising a hot subdwarf paired with a bright main-sequence/giant companion display short-period photometric variations possibly due to irradiation or stellar activity and are also short-period candidates. All except two candidates were drawn from a selection of subluminous stars in the Galaxy Evolution Explorer ultraviolet sky survey. Our new identifications also include a low-mass subdwarf B star and likely progenitor of a low-mass white dwarf (GALEX J0805-1058) paired with an unseen, possibly substellar, companion. The mass functions of the newly identified binaries imply minimum secondary masses ranging from 0.03 to 0.39M⊙. Photometric time series suggest that, apart from GALEX J0805-1058 and J2205-3141, the companions are most likely white dwarfs. We update the binary population statistics: close to 40 per cent of hot subdwarfs have a companion. Also, we found that the secondary mass distribution shows a lowmass peak attributed to late-type dwarfs, and a higher mass peak and tail distribution attributed to white dwarfs and a few spectroscopic composites. Also, we found that the population kinematics imply an old age and include a few likely halo population members. |
Keywords | binaries: close; binaries: spectroscopic; subdwarfs; white dwarfs; ultraviolet: stars |
Related Output | |
Is obsoleted by | Erratum: New binaries among UV-selected, hot subdwarf stars and population properties |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Byline Affiliations | Czech Academy of Sciences, Czech Republic |
Australian Astronomical Observatory, Australia | |
University of Erlangen–Nuremberg, Germany | |
School of Agricultural, Computational and Environmental Sciences | |
University of Cape Town, South Africa | |
South African Astronomical Observatory, South Africa | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q3052/new-binaries-among-uv-selected-hot-subdwarf-stars-and-population-properties
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