A Caltech Library Service

The shortest period detached white dwarf + main-sequence binary

Parsons, S. G. and Marsh, T. R. and Gänsicke, B. T and Dhillon, V. S. and Copperwheat, C. M. and Littlefair, S. P. and Pyrzas, S. and Drake, A. J. and Koester, D. and Schreiber, M. R. and Rebassa-Mansergas, A. (2012) The shortest period detached white dwarf + main-sequence binary. Monthly Notices of the Royal Astronomical Society, 419 (1). pp. 304-313. ISSN 0035-8711.

PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


We present high-speed ULTRACAM and SOFI photometry and X-shooter spectroscopy of the recently discovered 94-min orbital period eclipsing white dwarf/main-sequence binary SDSS J085746.18+034255.3 (CSS 03170) and use these observations to measure the system parameters. We detect a shallow secondary eclipse and hence are able to determine an orbital inclination of i = 85º.5 ± 0º.2. The white dwarf has a mass of 0.51 ± 0.05 M_⊙ and a radius of 0.0247 ± 0.0008 R_⊙. With a temperature of 35 300 ± 400 K the white dwarf is highly overinflated if it has a carbon–oxygen core; however, if it has a helium core then its mass and radius are consistent with evolutionary models. Therefore, the white dwarf in SDSS J085746.18+034255.3 is most likely a helium core white dwarf with a mass close to the upper limit expected from evolution. The main-sequence star is an M8 dwarf with a mass of 0.09 ± 0.01 M_⊙ and a radius of 0.110 ± 0.004 R_⊙ placing it close to the hydrogen burning limit. The system emerged from a common envelope ∼20 million years ago and will reach a semidetached configuration in ∼400 million years, becoming a cataclysmic variable with a period of 66 min, below the period minimum.

Item Type:Article
Related URLs:
URLURL TypeDescription
Marsh, T. R.0000-0002-2498-7589
Gänsicke, B. T0000-0002-2761-3005
Littlefair, S. P.0000-0001-7221-855X
Additional Information:© 2011 The Authors. Monthly Notices of the Royal Astronomical Society © 2011 RAS. Accepted 2011 August 24. Received 2011 August 15; in original form 2011 June 24. Article first published online: 29 Sep 2011. ULTRACAM, TRM, BTG, CMC, VSD and SPL are supported by the Science and Technology Facilities Council (STFC). SPL also acknowledges the support of an RCUK Fellowship. AR-M acknowledges financial support from FONDECYT in the form of grant number 3110049. MRS thanks for support from FONDECYT (1100782). The results presented in this paper are based on observations collected at the European Southern Observatory under programme IDs 086.D-0265, 286.D-5030 and 087.D-0046.
Funding AgencyGrant Number
Science and Technology Facilities Council (STFC)UNSPECIFIED
Subject Keywords: binaries: eclipsing; stars: fundamental parameters; stars: individual: CSS 03170; stars: low-mass; white dwarfs
Issue or Number:1
Record Number:CaltechAUTHORS:20120224-143120602
Persistent URL:
Official Citation:Parsons, S. G., Marsh, T. R., Gänsicke, B. T., Dhillon, V. S., Copperwheat, C. M., Littlefair, S. P., Pyrzas, S., Drake, A. J., Koester, D., Schreiber, M. R. and Rebassa-Mansergas, A. (2012), The shortest period detached white dwarf + main-sequence binary. Monthly Notices of the Royal Astronomical Society, 419: 304–313. doi: 10.1111/j.1365-2966.2011.19691.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29465
Deposited By: Ruth Sustaita
Deposited On:24 Feb 2012 23:31
Last Modified:09 Mar 2020 13:19

Repository Staff Only: item control page