K2-290: a warm Jupiter and a mini-Neptune in a triple-star system
Kuzuhara, M.; Alonso, R.; Deeg, H.; Erikson, A.; Fridlund, M.; Pätzold, M.; Rauer, H.; Barragán, O.; Dai, F.; Gandolfi, D.; Hirano, T.; Korth, J.; Prieto-Arranz, J.; Nespral, D.; Antoniciello, G.; Hjorth, M.; Grziwa, S.; Albrecht, S.; Hatzes, A. P.; Smith, A. M. S.; Cabrera, J.; Narita, N.; Cochran, W. D.; Palle, E.; Persson, C. M.; Van Eylen, V.; Nowak, G.; Winn, J. N.; Esposito, M.; Lam, K. W. F.; Luque, R.; Redfield, S.; Rodler, F.; Csizmadia, Sz; Hidalgo, D.; Justesen, A. B.; Trifonov, T.; Endl, M.; Guenther, E.; Livingston, J. H.; Montanes-Rodriguez, P.; de Leon, J.; Eigmüller, Ph; Heeren, P.
Denmark, Japan, Italy, United States, Spain, Germany, Chile, Sweden, Netherlands
Abstract
We report the discovery of two transiting planets orbiting K2-290 (EPIC 249624646), a bright (V = 11.11) late F-type star residing in a triple-star system. It was observed during Campaign 15 of the K2 mission, and in order to confirm and characterize the system, follow-up spectroscopy and AO imaging were carried out using the FIES, HARPS, HARPS-N, and IRCS instruments. From AO imaging and Gaia data we identify two M-dwarf companions at a separation of 113 ± 2 and 2467_{-155}^{+177} au. From radial velocities, K2 photometry, and stellar characterization of the host star, we find the inner planet to be a mini-Neptune with a radius of 3.06 ± 0.16 R⊕ and an orbital period of P = 9.2 d. The radius of the mini-Neptune suggests that the planet is located above the radius valley, and with an incident flux of F ∼ 400 F⊕, it lies safely outside the super-Earth desert. The outer warm Jupiter has a mass of 0.774 ± 0.047 MJ and a radius of 1.006 ± 0.050 RJ, and orbits the host star every 48.4 d on an orbit with an eccentricity e < 0.241. Its mild eccentricity and mini-Neptune sibling suggest that the warm Jupiter originates from in situ formation or disc migration.