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A magnetic accretion switch in pre-cataclysmic binaries
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Drake, Jeremy J., Garraffo, Cecilia, Takei, Dai and Gaensicke, B. T. (Boris T.) (2014) A magnetic accretion switch in pre-cataclysmic binaries. Monthly Notices of the Royal Astronomical Society, Volume 437 (Number 4). pp. 3842-3847. doi:10.1093/mnras/stt2186
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Official URL: http://dx.doi.org/10.1093/mnras/stt2186
Abstract
We have investigated the mass accretion rate implied by published surface abundances of Si and C in the white dwarf component of the 3.62 h period pre-cataclysmic binary and planet host candidate QS Vir (DA+M2−4). Diffusion time-scales for gravitational settling imply M˙∼10−16M⊙ yr−1 for the 1999 epoch of the observations, which is three orders of magnitude lower than measured from a 2006 XMM–Newton observation. This is the first time that large accretion rate variations have been seen in a detached pre-cataclysmic variable (pre-CV). A third body in a 14 yr eccentric orbit suggested in a recent eclipse timing study is too distant to perturb the central binary sufficiently to influence accretion. A hypothetical coronal mass ejection just prior to the XMM–Newton observation might explain the higher accretion rate, but the implied size and frequency of such events appear too great. We suggest accretion is most likely modulated by a magnetic cycle on the secondary acting as a wind ‘accretion switch’, a mechanism that can be tested by X-ray and ultraviolet monitoring. If so, QS Vir and similar pre-CVs could provide powerful insights into hitherto inscrutable CV and M dwarf magnetospheres, and mass- and angular-momentum-loss rates.
| Item Type: | Journal Article | ||||
|---|---|---|---|---|---|
| Subjects: | Q Science > QB Astronomy | ||||
| Divisions: | Faculty of Science > Physics | ||||
| Library of Congress Subject Headings (LCSH): | Accretion (Astrophysics), Eclipsing binaries, Stars, New | ||||
| Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society | ||||
| Publisher: | Oxford University Press | ||||
| ISSN: | 0035-8711 | ||||
| Official Date: | 2014 | ||||
| Dates: |
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| Volume: | Volume 437 | ||||
| Number: | Number 4 | ||||
| Number of Pages: | 6 | ||||
| Page Range: | pp. 3842-3847 | ||||
| DOI: | 10.1093/mnras/stt2186 | ||||
| Status: | Peer Reviewed | ||||
| Publication Status: | Published | ||||
| Access rights to Published version: | Restricted or Subscription Access | ||||
| Funder: | United States. National Aeronautics and Space Administration (NASA) |
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