New binaries among UV-selected, hot subdwarf stars and population properties

0449327 - ASÚ 2016 RIV GB eng J - Článek v odborném periodiku
Kawka, Adela - Vennes, Stephane - O' Toole, S. - Németh, P. - Burton, D. - Kotze, E. - Buckley, D.A.H.
New binaries among UV-selected, hot subdwarf stars and population properties.
Monthly Notices of the Royal Astronomical Society. Roč. 450, č. 4 (2015), s. 3514-3548. ISSN 0035-8711. E-ISSN 1365-2966
Grant CEP: GA ČR GAP209/12/0217; GA ČR GA13-14581S; GA MŠMT LG14013
Institucionální podpora: RVO:67985815
Klíčová slova: close binaries * spectroscopic * subdwarfs
Kód oboru RIV: BN - Astronomie a nebeská mechanika, astrofyzika
Impakt faktor: 4.952, rok: 2015

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. 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. 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 low-mass 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.
Trvalý link: http://hdl.handle.net/11104/0250881