Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 1K074

A new, low-mass, pre-main sequence eclipsing binary with evidence of a circumbinary disk

Gillen, Ed (University of Oxford, Dept. of Physics)
Aigrain, Suzanne (University of Oxford, Dept. of Physics)
McQuillan, Amy (University of Oxford, Dept. of Physics)
Bouvier, Jerome (Laboratoire d\'Astrophysique de Grenoble)
Hodgkin, Simon (Institute of Astronomy, University of Cambridge)
Alencar, Silvia (Universidade Federal de Minas Gerais)
Terquem, Caroline (University of Oxford, Dept. of Physics)
Southworth, John (Astrophysics Group, Keele University)
Gibson, Neale (ESO, Garching)
Cody, Ann Marie (Spitzer Science Centre, Caltech)
Lendl, Monika (Observatoire de Genève, Université de Genève)
Morales-Calderón, Maria (Centro de Astrobiología (INTA-CSIC))
Favata, Fabio (ESA)
Stauffer, John (Spitzer Science Centre, Caltech)
Micela, Giusi (Observatorio Astronomico di Palermo)

We present the discovery of a double-lined, detached eclipsing binary (EB), comprising two pre-main sequence M-dwarfs, in the 3 Myr old NGC 2264 star-forming region. Eclipses were detected in this system, during a continuous 23-day observation of NGC 2264 by the CoRoT space mission in 2008. Multi-epoch optical and near-IR follow-up spectroscopy with VLT/FLAMES and WHT/ISIS yielded a full orbital solution. We derive fundamental stellar parameters by modelling the light curve and radial velocity data, finding that the two stars travel on essentially circular orbits with a period of 3.8745745 ± 0.0000014 days and have masses of 0.67 ± 0.01 and 0.495 ± 0.007 M_sun with corresponding radii of 1.30 ± 0.04 and 1.11 ± 0.05 R_sun. The CoRoT light curve also contains large-amplitude, rapidly evolving out-of-eclipse variations, which are difficult to explain with star spots alone. SED modelling of the system’s broadband optical and infrared magnitudes reveals a mid-IR excess, which we model as emission from a small amount of dust located within the inner cavity of a circumbinary disk. In turn, this opens up the possibility that some of the out-of-eclipse variability could be due to occultations of the central stars by material located at the inner edge or in the central cavity of the circumbinary disk.

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