Volume 558, October 2013
|Number of page(s)||8|
|Section||Stellar structure and evolution|
|Published online||04 October 2013|
One, two, or three stars? An investigation of an unusual eclipsing binary candidate undergoing dramatic period changes⋆
1 Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK
2 The British Astronomical Association, Burlington House, Piccadilly, London W1J 0DU, UK
Received: 26 July 2013
Accepted: 29 August 2013
We report our investigation of 1SWASP J234401.81−212229.1, a variable with a 18 461.6 s period. After identification in a 2011 search of the SuperWASP archive for main-sequence eclipsing binary candidates near the distribution’s short-period limit of ~0.20 d, it was measured to be undergoing rapid period decrease in our earlier work, though later observations supported a cyclic variation in period length. Spectroscopic data obtained in 2012 with the Southern African Large Telescope did not, however, support the interpretation of the object as a normal eclipsing binary. Here, we consider three possible explanations consistent with the data: a single-star oblique rotator model in which variability results from stable cool spots on opposite magnetic poles; a two-star model in which the secondary is a brown dwarf; and a three-star model involving a low-mass eclipsing binary in a hierarchical triple system. We conclude that the latter is the most likely model.
Key words: stars: individual: 1SWASP J234401.81 / 212229.1 / stars: variables: general / binaries: close / binaries: eclipsing
Table 2 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/558/A71
© ESO, 2013
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