Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune

Barragán, O.; Aigrain, S.; Kubyshkina, D.; Gandolfi, D.; Livingston, J.; Fridlund, M. C. V.; Fossati, L.; Korth, J.; Parviainen, H.; Malavolta, L.; Palle, E.; Deeg, H. J.; Nowak, G.; Rajpaul, V. M.; Zicher, N.; Antoniciello, G.; Narita, N.; Albrecht, S.; Bedin, L. R.; Cabrera, J.; Cochran, W. D.; de Leon, J.; Eigmüller, Ph; Fukui, A.; Granata, V.; Grziwa, S.; Guenther, E.; Hatzes, A. P.; Kusakabe, N.; Latham, D. W.; Libralato, M.; Luque, R.; Montañés-Rodríguez, P.; Murgas, F.; Nardiello, D.; Pagano, I.; Piotto, G.; Persson, C. M.; Redfield, S.; Tamura, M.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society

Advertised on:
11
2019
Number of authors
40
IAC number of authors
8
Citations
56
Refereed citations
52
Description
We present a detailed analysis of HARPS-N radial velocity observations of K2-100, a young and active star in the Praesepe cluster, which hosts a transiting planet with a period of 1.7 d. We model the activity-induced radial velocity variations of the host star with a multidimensional Gaussian Process framework and detect a planetary signal of 10.6 ± 3.0 {m s^{-1}}, which matches the transit ephemeris, and translates to a planet mass of 21.8 ± 6.2 M⊕. We perform a suite of validation tests to confirm that our detected signal is genuine. This is the first mass measurement for a transiting planet in a young open cluster. The relatively low density of the planet, 2.04 _{ - 0.61 } ^ { + 0.66 } {g cm^{-3}}, implies that K2-100b retains a significant volatile envelope. We estimate that the planet is losing its atmosphere at a rate of 10^{11}-10^{12} {g s^{-1}} due to the high level of radiation it receives from its host star.
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