K2-290: a warm Jupiter and a mini-Neptune in a triple-star system
Journal article, 2019

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 246-155+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.

planets and satellites: individual: EPIC 249624646

planets and satellites: detection

planets and satellites: formation

planets and satellites: individual: K2-290


M. Hjorth

A.B. Justesen

T. Hirano

S. Albrecht

D. Gandolfi

F. Dai

R. Alonso

O. Barragan

M. Esposito

M. Kuzuhara

K.W.F. Lam

J.H. Livingston

P. Montanés Rodríguez

N. Narita

G. Nowak

J. Prieto-Arranz

S. Redfield

F. Rodler

V. Van Eylen

J. N. Winn

G. Antoniciello

J. Cabrera

W. D. Cochran

Sz. Csizmadia

J. P. de Leon

H. Deeg

Ph Eigmüller

M. Endl

A. Erikson

Malcolm Fridlund

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

S. Grziwa

E. Guenther

A. P. Hatzes

P. Heeren

D. Hidalgo

J. Korth

R. Luque

D. Nespral

M. Pätzold

Carina Persson

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Galactic Astrophysics

H. Rauer

A. M. S. Smith

T. Trifonov

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 484 3 3522-3536

Exoplanets from space – CHEOPS and PLATO, ESA’s next two projects

Swedish National Space Board, 2017-01-01 -- 2022-12-31.

Subject Categories

Astronomy, Astrophysics and Cosmology


Basic sciences



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