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X-ray orbital modulation of a white dwarf accreting from an L dwarf: The system SDSS J121209.31+013627.7

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journal contribution
posted on 17.03.2017, 12:35 by B. Stelzer, D. De Martino, S. L. Casewell, G. A. Wynn, M. Roy
In an XMM-Newton observation of the binary SDSS J121209.31+013627.7, consisting of a white dwarf and an L dwarf, we detect X-ray orbital modulation as proof of accretion from the substellar companion onto the magnetic white dwarf. We constrain the system geometry (inclination as well as magnetic and pole-cap angle) through modelling of the X-ray light curve, and we derive a mass accretion rate of 3.2 × 10-14MȮ/ yr from the X-ray luminosity (~3 × 1029 erg/s). From X-ray studies of L dwarfs, a possible wind driven from a hypothesized corona on the substellar donor is orders of magnitude too weak to explain the observed accretion rate, while the radius of the L dwarf is comparable to its Roche lobe (0.1 RȮ), making Roche-lobe overflow the likely accretion mechanism in this system.

Funding

DDM acknowledges financial support from ASI INAF I/037/12/0. SLC acknowledges support from the University of Leicester College of Science and Engineering.

History

Citation

Astronomy and Astrophysics, 2017, 598, L6

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Astronomy and Astrophysics

Publisher

EDP Sciences for European Southern Observatory (ESO), Springer Verlag

issn

0004-6361

eissn

1432-0746

Copyright date

2017

Available date

17/03/2017

Publisher version

http://www.aanda.org/articles/aa/abs/2017/02/aa30038-16/aa30038-16.html

Language

en