K2-140b and K2-180b - Characterization of a hot Jupiter and a mini-Neptune from the K2 mission
Journal article, 2018

We report the independent discovery and characterization of two K2 planets: K2-180b, a mini-Neptune-sized planet in an 8.9-d orbit transiting a V = 12.6 mag, metal-poor ([Fe/H] = -0.65 ± 0.10) K2V star in K2 campaign 5; K2-140b, a transiting hot Jupiter in a 6.6-d orbit around a V = 12.6 mag G6V ([Fe/H] = + 0.10 ± 0.10) star in K2 campaign 10. Our results are based on K2 time-series photometry combined with high-spatial resolution imaging and high-precision radial velocity measurements. We present the first mass measurement of K2-180b. K2-180b has a mass of Mp = 11.3 ± 1.9 M_Earth and a radius of Rp = 2.2 ± 0.1 R_Earth, yielding a mean density of ρp = 5.6 ± 1.9 g cm-3, suggesting a rocky composition. Given its radius, K2-180b is above the region of the so-called `planetary radius gap'. K2-180b is in addition not only one of the densest mini-Neptune-sized planets, but also one of the few mini-Neptune-sized planets known to transit a metal-poor star. We also constrain the planetary and orbital parameters of K2-140b and show that, given the currently available Doppler measurements, the eccentricity is consistent with zero, contrary to the results of a previous study.

stars: individual: K2-140

stars: individual: K2-180

planets and satellites: fundamental parameters

techniques: radial velocities

techniques: photometric

stars: fundamental parameters


M. Pätzold

Carina Persson

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

J. Livingston

J. Korth

D. Gandolfi

Malcolm Fridlund

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

Sz. Csizmadia

T. Hirano

H. J. Deeg

A.B. Justesen

O. Barragan

S. Grziwa

M. Endl

R. Tronsgaard

F. Dai

W. D. Cochran

S. Albrecht

R. Alonso

J. Cabrera

P.W. Cauley

F. Cusano

Ph Eigmüller

A. Erikson

M. Esposito

E. W. Guenther

A. P. Hatzes

D. Hidalgo

M. Kuzuhara

P. Montañes

N.R. Napolitano

N. Narita

P. Niraula

D. Nespral

G. Nowak

E. Palle

C.E. Petrillo

S. Redfield

J. Prieto-Arranz

H. Rauer

A. M. S. Smith

C. Tortora

V. Van Eylen

J. N. Winn

Monthly Notices of the Royal Astronomical Society

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

Vol. 482 2 1807-1823

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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