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Hot subdwarfs in close binaries observed from space : II. Analyses of the light variations
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Schaffenroth, V., Barlow, B. N., Pelisoli, I., Geier, S. and Kupfer, T. (2023) Hot subdwarfs in close binaries observed from space : II. Analyses of the light variations. Astronomy & Astrophysics, 673 . A90. doi:10.1051/0004-6361/202244697 ISSN 0004-6361.
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Official URL: http://dx.doi.org/10.1051/0004-6361/202244697
Abstract
Context. Hot subdwarfs in close binaries with either M dwarf, brown dwarf, or white dwarf companions show unique light variations. In hot subdwarf binaries with M dwarf or brown dwarf companions, we can observe the so-called reflection effect, while in hot subdwarfs with close white dwarf companions, we find ellipsoidal modulation and/or Doppler beaming.
Aims. Analyses of these light variations can be used to derive the mass and radius of the companion and determine its nature. Thereby, we can assume the most probable sdB mass and the radius of the sdB derived by the fit of the spectral energy distribution and the Gaia parallax.
Methods. In the high signal-to-noise space-based light curves from the Transiting Exoplanet Survey Satellite and the K2 space mission, several reflection effect binaries and ellipsoidal modulation binaries have been observed with much better quality than with ground-based observations. The high quality of the light curves allowed us to analyze a large sample of sdB binaries with M dwarf or white dwarf companions using LCURVE.
Results. For the first time, we can constrain the absolute parameters of 19 companions of reflection effect systems, covering periods from 2.5 to 19 h and with companion masses from the hydrogen-burning limit to early M dwarfs. Moreover, we were able to determine the mass of eight white dwarf companion to hot subdwarf binaries showing ellipsoidal modulations, covering the as-yet unexplored period range of 7 to 19 h. The derived masses of the white dwarf companions show that all but two of the white dwarf companions are most likely helium-core white dwarfs. Combining our results with previously measured rotation velocities allowed us to derive the rotation period of seven sdBs in short-period binaries. In four of those systems, the rotation period of the sdB agrees with a tidally locked orbit, whereas in the other three systems, the sdB rotates significantly more slowly.
Item Type: | Journal Article | |||||||||||||||||||||||||||||||||
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Subjects: | Q Science > QB Astronomy | |||||||||||||||||||||||||||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | |||||||||||||||||||||||||||||||||
Library of Congress Subject Headings (LCSH): | Double stars , Double stars -- Motion in line of sight, Low mass stars , Doppler effect | |||||||||||||||||||||||||||||||||
Journal or Publication Title: | Astronomy & Astrophysics | |||||||||||||||||||||||||||||||||
Publisher: | EDP Sciences | |||||||||||||||||||||||||||||||||
ISSN: | 0004-6361 | |||||||||||||||||||||||||||||||||
Official Date: | May 2023 | |||||||||||||||||||||||||||||||||
Dates: |
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Volume: | 673 | |||||||||||||||||||||||||||||||||
Article Number: | A90 | |||||||||||||||||||||||||||||||||
DOI: | 10.1051/0004-6361/202244697 | |||||||||||||||||||||||||||||||||
Status: | Peer Reviewed | |||||||||||||||||||||||||||||||||
Publication Status: | Published | |||||||||||||||||||||||||||||||||
Access rights to Published version: | Open Access (Creative Commons) | |||||||||||||||||||||||||||||||||
Date of first compliant deposit: | 25 July 2023 | |||||||||||||||||||||||||||||||||
Date of first compliant Open Access: | 26 July 2023 | |||||||||||||||||||||||||||||||||
RIOXX Funder/Project Grant: |
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