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

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

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


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+177155 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.

Original languageEnglish (US)
Pages (from-to)3522-3536
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Apr 11 2019

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planets
  • Planets and satellites: detection
  • Planets and satellites: formation
  • Planets and satellites: individual: K2-290
  • Satellites: individual: EPIC 249624646


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