EPIC 201702477b: A Transiting Brown Dwarf from K2 in a 41 day Orbit

Bayliss, D. and Hojjatpanah, S. and Santerne, A. and Dragomir, D. and Zhou, G. ORCID: https://orcid.org/0000-0002-4891-3517 and Shporer, A. and Colon, K. D. and Almenara, J. and Armstrong, D. J. and Barrado, D. and Barros, S. C. C. and Bento, J. and Boisse, I. and Bouchy, F. and Brown, D. J. A. and Brown, T. and Cameron, A. and Cochran, W. D. and Demangeon, O. and Deleuil, M. and Diaz, R. F. and Fulton, B. and Horne, K. and Hebrard, G. and Lillo-Box, J. and Lovis, C. and Mawet, D. and Ngo, H. and Osborn, H. and Palle, E. and Petigura, E. and Pollacco, D. and Santos, N. and Sefako, R. and Siverd, R. and Sousa, S. G. and Tsantaki, M. (2016) EPIC 201702477b: A Transiting Brown Dwarf from K2 in a 41 day Orbit. The Astronomical Journal, 153 (1):15. pp. 1-10. ISSN 0004-6256

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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 M J, 0.757 ±0.065 R J, 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 M J. This may be the signature of mass-dependent ejection of systems during the formation process.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 03 Feb 2022 02:28
Last Modified: 07 Feb 2022 00:05
Uncontrolled Keywords: planetary systems; techniques: photometric; techniques: spectroscopic; Astrophysics - Earth and Planetary Astrophysics
Fields of Research (2008): 02 Physical Sciences > 0201 Astronomical and Space Sciences > 020110 Stellar Astronomy and Planetary Systems
Fields of Research (2020): 51 PHYSICAL SCIENCES > 5101 Astronomical sciences > 510109 Stellar astronomy and planetary systems
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970102 Expanding Knowledge in the Physical Sciences
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280120 Expanding knowledge in the physical sciences
Identification Number or DOI: https://doi.org/10.3847/1538-3881/153/1/15
URI: http://eprints.usq.edu.au/id/eprint/44966

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