Rebassa-Mansergas, A., Hollands, M., Parsons, S.G. orcid.org/0000-0002-2695-2654 et al. (6 more authors) (2024) J0526+5934: a peculiar ultra-short-period double white dwarf. Astronomy & Astrophysics, 686. A221. ISSN 0004-6361
Abstract
Context. Ultra-short-period compact binaries are important sources of gravitational waves. The class of short-period compact binaries includes, for example, the progenitors of type Ia supernovae and the progenitors of merger episodes that may lead to massive and magnetic single white dwarfs. J0526+5934 is one such example: it is an unresolved compact binary star with an orbital period of 20.5 min.
Aims. The visible component of J0526+5934 was recently claimed to be a hot sub-dwarf star with a CO white dwarf companion. Our aim is to provide strong observational and theoretical evidence that the primary star is instead an extremely low-mass white dwarf, although the hot sub-dwarf nature cannot be completely ruled out.
Methods. We analysed optical spectra together with time-series photometry of the visible component of J0526+5934 to constrain its orbital and stellar parameters. We also employed evolutionary sequences for low-mass white dwarfs to derive independent values of the primary mass.
Results. From the analysis of our observational data, we find a stellar mass for the primary star in J0526+5934 of 0.26 ± 0.05 M⊙, which perfectly matches the 0.237 ± 0.035 M⊙ independent measurement we derive from the theoretical evolutionary models. This value is considerably lower than the theoretically expected and generally observed mass range for hot sub-dwarf stars, but falls well within the mass limit values of extremely low-mass white dwarfs.
Conclusions. We conclude J0526+5934 is the sixth ultra-short-period detached double white dwarf currently known.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Authors 2024. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
Keywords: | Astronomical Sciences; Physical Sciences; binaries: close; white dwarfs |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Funding Information: | Funder Grant number SCIENCE AND TECHNOLOGY FACILITIES COUNCIL ST/R003424/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 06 Aug 2024 10:28 |
Last Modified: | 06 Aug 2024 10:28 |
Status: | Published |
Publisher: | EDP Sciences |
Refereed: | Yes |
Identification Number: | 10.1051/0004-6361/202449519 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:215483 |