Radial velocity confirmation of K2-100b: a young, highly irradiated, and low-density transiting hot Neptune. Issue 1 (13th September 2019)

• Record Type: Journal Article
• Authors: 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;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 490:Issue 1(2019)
• Page Start: 698
• Page End: 708
• Publication Date: 2019-09-13
• Subjects: planets and satellites: individual: K2-100b -- techniques: photometric -- techniques: radial velocities; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stz2569
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: 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 ${\rm m\, s^{-1}}$, 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, $2.04 _{ - 0.61 } ^ { + 0.66 }$ ${\rm g\, cm^{-3}}$, implies that K2-100b retains a significant volatile envelope. We estimate that the planet is losing its atmosphere at a rate of $10^{11}\!-\!10^{12}\, {\rm g\, s^{-1}}$ due to the high level of radiation it receives from its host star.