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A Low-mass Exoplanet Candidate Detected by K2 Transiting the Praesepe M Dwarf JS 183

Pepper, Joshua and Gillen, Ed and Parviainen, Hannu and Hillenbrand, Lynne A. and Cody, Ann Marie and Aigrain, Suzanne and Stauffer, John and Vrba, Frederick J. and David, Trevor and Lillo-Box, Jorge and Stassun, Keivan G. and Conroy, Kyle E. and Pope, Benjamin J. S. and Barrado y Navascués, David (2017) A Low-mass Exoplanet Candidate Detected by K2 Transiting the Praesepe M Dwarf JS 183. Astronomical Journal, 153 (4). Art. No. 177. ISSN 1538-3881.

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We report the discovery of a repeating photometric signal from a low-mass member of the Praesepe open cluster that we interpret as a Neptune-sized transiting planet. The star is JS 183 (HSHJ 163, EPIC 211916756), with T_(eff) = 3325 ± 100 K, M* = 0.44 ± 0.04 M⊙, R* = 0.44 ± 0.03 R⊙, and log g* = 4.82 ± 0.06. The planet has an orbital period of 10.134588 days and a radius of R_P = 0.32 ± 0.02 R_J. Since the star is faint at V = 16.5 and J = 13.3, we are unable to obtain a measured radial velocity orbit, but we can constrain the companion mass to below about 1.7 M J, and thus well below the planetary boundary. JS 183b (since designated as K2-95b) is the second transiting planet found with K2 that resides in a several-hundred-megayear open cluster; both planets orbit mid-M dwarf stars and are approximately Neptune sized. With a well-determined stellar density from the planetary transit, and with an independently known metallicity from its cluster membership, JS 183 provides a particularly valuable test of stellar models at the fully convective boundary. We find that JS 183 is the lowest-density transit host known at the fully convective boundary, and that its very low density is consistent with current models of stars just above the fully convective boundary but in tension with the models just below the fully convective boundary.

Item Type:Article
Related URLs:
URLURL TypeDescription
Pepper, Joshua0000-0002-3827-8417
Gillen, Ed0000-0003-2851-3070
Cody, Ann Marie0000-0002-3656-6706
Aigrain, Suzanne0000-0003-1453-0574
Stauffer, John0000-0003-3595-7382
David, Trevor0000-0001-6534-6246
Stassun, Keivan G.0000-0002-3481-9052
Conroy, Kyle E.0000-0002-5442-8550
Additional Information:© 2017 The American Astronomical Society. Received 2016 July 8; revised 2017 February 2; accepted 2017 February 5; published 2017 March 24. J.P. would like to thank Ian Crossfield for useful discussions. T.D. is supported by an NSF Graduate Research Fellowship under grant DGE1144469. B.J.S.P. would like to thank Balliol College and the Clarendon Fund for their financial support of this work. S.A. and H.P. acknowledge funding from the Leverhulme Trust. S.A. received support from the UK Science and Technology Facilities Council (STFC). K.G.S. acknowledges partial support through NSF PAARE grant AST-1358862. J.L.-B. acknowledges support from the Marie Curie Actions of the European Commission (FP7-COFUND).
Group:Astronomy Department
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1144469
Balliol CollegeUNSPECIFIED
Leverhulme TrustUNSPECIFIED
Science and Technology Facilities Council (STFC)UNSPECIFIED
Marie Curie FellowshipUNSPECIFIED
Subject Keywords:galaxies: star clusters: individual (Praesepe) – planets and satellites: detection
Issue or Number:4
Record Number:CaltechAUTHORS:20170327-101601263
Persistent URL:
Official Citation:Joshua Pepper et al 2017 AJ 153 177
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75411
Deposited By: Tony Diaz
Deposited On:27 Mar 2017 19:12
Last Modified:03 Oct 2019 16:50

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