Burleigh, M.R., Marsh, T.R., Gänsicke, B.T. et al. (16 more authors) (2006) The nature of the close magnetic white dwarf + probable brown dwarf binary SDSS J121209.31+013627.7. Monthly Notices of the Royal Astronomical Society, 373 (4). pp. 1416-1422. ISSN 0035-8711
Abstract
Optical time series photometry of the short-period magnetic white dwarf + probable brown dwarf binary SDSS J121209.31+013627.7 reveals pulse-like variability in all bands from i to u , increasing towards bluer wavelengths and peaking at u . These modulations are most likely due to a self-eclipsing accretion hot spot on the white dwarf, rotating into view every 88.43 min. This period is commensurate with the Hα radial velocity period of ≈90 min, and consistent with the rotation period of the accretor being equal to the binary orbital period. We combine our observations with other recently reported results to provide an accurate ephemeris. We also detect the system in X-rays with Swift, and estimate the accretion rate at ≈10−13 M� yr−1. We suggest that SDSS J121209.31+013627.7 is most likely a magnetic cataclysmic variable in an extended state of very low accretion, similar to the well-studied polar EF Eri. Alternatively, the putative brown dwarf is not filling its Roche lobe and the system is a detached binary in which the white dwarf is efficiently accreting from the wind of the secondary. However, it is unclear whether an L dwarf wind is strong enough to provide the measured accretion rate. We suggest further observations to distinguish between the Roche lobe overflow and wind accretion scenarios.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Editors: |
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Copyright, Publisher and Additional Information: | © 2006 The Authors. Journal compilation. © 2006 RAS. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | stars: low-mass; brown dwarfs – novae; cataclysmic variables – 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) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 10 Apr 2019 10:20 |
Last Modified: | 10 Apr 2019 10:41 |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1111/j.1365-2966.2006.11030.x |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:144703 |