Verf.angabe: | A.M.S. Smith, D. Gandolfi, O. Barragán, B. Bowler, Sz. Csizmadia, M. Endl, M.C.V. Fridlund, S. Grziwa, E. Guenther, A.P. Hatzes, G. Nowak, S. Albrecht, R. Alonso, J. Cabrera, W.D. Cochran, F. Cusano, H.J. Deeg, Ph Eigmüller, A. Erikson, D. Hidalgo, T. Hirano, M.C. Johnson, J. Korth, A. Mann, N. Narita, D. Nespral, E. Palle, M. Pätzold, J. Prieto-Arranz, H. Rauer, I. Ribas, B. Tingley, and V. Wolthoff |
Abstract: | We report the discovery from K2 of a transiting planet in an 18.25-d, eccentric (0.19$\pm$ 0.04) orbit around K2-99, an 11th magnitude subgiant in Virgo. We confirm the planetary nature of the companion with radial velocities, and determine that the star is a metal-rich ([Fe/H] = 0.20$\pm$0.05) subgiant, with mass $1.60^{+0.14}_{-0.10}~M_\odot$ and radius $3.1\pm 0.1~R_\odot$. The planet has a mass of $0.97\pm0.09~M_{\rm Jup}$ and a radius $1.29\pm0.05~R_{\rm Jup}$. A measured systemic radial acceleration of $-2.12\pm0.04~{\rm m s^{-1} d^{-1}}$ offers compelling evidence for the existence of a third body in the system, perhaps a brown dwarf orbiting with a period of several hundred days. |