Parameters of two low-mass contact eclipsing binaries near the short-period limit

¹ Department of Physical SciencesThe Open University, Walton Hall, Milton Keynes MK7 6AA, UK
e-mail: Marcus.Lohr@open.ac.uk
² Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK

Received: 21 May 2013
Accepted: 31 January 2013

Abstract

The two objects 1SWASP J150822.80−054236.9 and 1SWASP J160156.04+202821.6 were initially detected from their SuperWASP archived light curves as candidate eclipsing binaries with periods close to the short-period cut-off of the orbital period distribution of main-sequence binaries, at ~0.2 d. Using spectroscopic data from the Isaac Newton Telescope in La Palma, Canary Islands, we here confirm them as double-lined spectroscopic and eclipsing binaries, in contact configuration. Following modelling of their visual light curves and radial velocity curves, we determine their component and system parameters to precisions between ~2 and 11%. The first system contains components of 1.07 and 0.55 M_⊙, with radii of 0.90 and 0.68 R_⊙, respectively; its primary exhibits pulsations with a period of 1/6 of the orbital period of the system. The latter contains components of 0.86 and 0.57 M_⊙, with radii of 0.75 and 0.63 R_⊙, respectively.