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Published February 2014 | Published + Submitted
Journal Article Open

CoRoT 223992193: A new, low-mass, pre-main sequence eclipsing binary with evidence of a circumbinary disk

Abstract

We present the discovery of CoRoT 223992193, a double-lined, detached eclipsing binary, comprising two pre-main sequence M dwarfs, discovered by the CoRoT space mission during a 23-day observation of the 3 Myr old NGC 2264 star-forming region. Using multi-epoch optical and near-IR follow-up spectroscopy with FLAMES on the Very Large Telescope and ISIS on the William Herschel Telescope we obtain a full orbital solution and derive the fundamental parameters of both stars by modelling the light curve and radial velocity data. The orbit is circular and has a period of 3.8745745 ± 0.0000014 days. The masses and radii of the two stars are 0.67 ± 0.01 and 0.495 ± 0.007 M_⊙ and 1.30 ± 0.04 and 1.11_(-0.05)^(+0.04) R_⊙, respectively. This system is a useful test of evolutionary models of young low-mass stars, as it lies in a region of parameter space where observational constraints are scarce; comparison with these models indicates an apparent age of ~3.5–6 Myr. The systemic velocity is within 1σ of the cluster value which, along with the presence of lithium absorption, strongly indicates cluster membership. The CoRoT light curve also contains large-amplitude, rapidly evolving out-of-eclipse variations, which are difficult to explain using starspots alone. The system's spectral energy distribution reveals a mid-infrared excess, which we model as thermal emission from a small amount of dust located in 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.

Additional Information

© 2014 ESO. Article published by EDP Sciences. Received 15 August 2013. Accepted 10 November 2013. Published online 05 February 2014. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESAs RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain. We thank Isabelle Baraffe for extending her models of stellar evolution (with mixing length ɑ = 1.9) down to lower masses allowing us to compare the source's masses and radii to these model predictions. We thank D. Barrado, the Director of Calar Alto Observatory, for granting Discretionary Time to this project. We also thank Catarina Alves de Oliveira for providing her automatic fitting method to derive the spectral type of the source from the Calar Alto low resolution spectrum. This research is based on data collected by the CoRoT satellite, which is publicly available via the IAS Data Center at http://idoc-corot.ias.u-psud.fr/. Based on observations made with ESO Telescopes at the La Silla Paranal Observatory under programme ID 088.C-0239(A). The WHT and INT are operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias. Based on observations collected at the Centro Astronómico Hispano Alemn (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). This work is based in part on observations made with the Spitzer Space Telescope, obtained from the NASA/IPAC Infrared Science Archive, both of which are operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space Administration. This work is based in part on observations made with Herschel, which is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. This publication makes use of data products from the 2MASS, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the NSF. This research has made use of the SIMBAD data base, operated at CDS, Strasbourg, France. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/, where the list of the funding organisations and collaborating institutions can be found. This work was supported in part by the UK Science and Technology Facilities Council through grant ST/G002266 (SA) and studentship ST/J500641/1 (EG). A.M. acknowledges support from a Science and Technology Facilities Council studentship. J.B. thanks CNES for the partial funding of this project. S.H.P.A. acknowledges financial support from CNPq, CAPES and Fapemig. J.S. acknowledges funding from STFC in the form of an Advanced Fellowship. Finally, we would like to thank the anonymous referee for his/her careful reading of the manuscript and helpful suggestions for improvement.

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August 19, 2023
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