EPIC 201702477b : a transiting brown dwarf from K2 in a 41 day orbit
Abstract
We report the discovery of EPIC 201702477b, a transiting brown dwarf in a long period (40.73691 ± 0.00037 day) and eccentric (e = 0.2281 ± 0.0026) orbit. This system was initially reported as a planetary candidate based on two transit events seen in K2 Campaign 1 photometry and later validated as an exoplanet candidate. We confirm the transit and refine the ephemeris with two subsequent ground-based detections of the transit using the Las Cumbres Observatory Global Telescope 1 m telescope network. We rule out any transit timing variations above the level of ∼30 s. Using high precision radial velocity measurements from HARPS and SOPHIE we identify the transiting companion as a brown dwarf with a mass, radius, and bulk density of 66.9 ± 1.7 MJ, 0.757 ± 0.065 RJ, and 191 ± 51 g cm-3 respectively. EPIC 201702477b is the smallest radius brown dwarf yet discovered, with a mass just below the H-burning limit. It has the highest density of any planet, substellar mass object, or main-sequence star discovered so far. We find evidence in the set of known transiting brown dwarfs for two populations of objects - high mass brown dwarfs and low mass brown dwarfs. The higher-mass population have radii in very close agreement to theoretical models, and show a lower-mass limit around 60 MJ. This may be the signature of mass-dependent ejection of systems during the formation process.
Citation
Bayliss , D , Hojjatpanah , S , Santerne , A , Dragomir , D , Zhou , G , Shporer , A , Colón , K D , Almenara , J , Armstrong , D J , Barrado , D , Barros , S C C , Bento , J , Boisse , I , Bouchy , F , Brown , D J A , Brown , T , Cameron , A , Cochran , W D , Demangeon , O , Deleuil , M , Díaz , R F , Fulton , B , Horne , K , Hébrard , G , Lillo-Box , J , Lovis , C , Mawet , D , Ngo , H , Osborn , H , Palle , E , Petigura , E , Pollacco , D , Santos , N , Sefako , R , Siverd , R , Sousa , S G & Tsantaki , M 2016 , ' EPIC 201702477b : a transiting brown dwarf from K2 in a 41 day orbit ' , Astronomical Journal , vol. 153 , no. 1 , 15 . https://doi.org/10.3847/1538-3881/153/1/15
Publication
Astronomical Journal
Status
Peer reviewed
ISSN
0004-6256Type
Journal article
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