K2-290: a warm Jupiter and a mini-Neptune in a triple-star system

Hjorth, M.; Justesen, A. B.; Hirano, T.; Albrecht, S.; Gandolfi, D.; Dai, F.; Alonso, R.; Barragán, O.; Esposito, M.; Kuzuhara, M.; Lam, K. W. F.; Livingston, J. H.; Montanes-Rodriguez, P.; Narita, N.; Nowak, G.; Prieto-Arranz, J.; Redfield, S.; Rodler, F.; Van Eylen, V.; Winn, J. N.; Antoniciello, G.; Cabrera, J.; Cochran, W. D.; Csizmadia, Sz; de Leon, J.; Deeg, H.; Eigmüller, Ph; Endl, M.; Erikson, A.; Fridlund, M.; Grziwa, S.; Guenther, E.; Hatzes, A. P.; Heeren, P.; Hidalgo, D.; Korth, J.; Luque, R.; Nespral, D.; Palle, E.; Pätzold, M.; Persson, C. M.; Rauer, H.; Smith, A. M. S.; Trifonov, T.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 484, Issue 3, p.3522-3536

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4
2019
Number of authors
44
IAC number of authors
10
Citations
22
Refereed citations
20
Description
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.
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