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Judith Korth



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


  • J. Korth
  • Sz Csizmadia
  • D. Gandolfi
  • M. Fridlund
  • M. Pätzold
  • T. Hirano
  • J. Livingston
  • C. M. Persson
  • H. J. Deeg
  • A. B. Justesen
  • O. Barragán
  • 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

Summary, in English

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=12.6mag, 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=12.6mag 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 ± 1.9M⊕ and a radius of Rp = 2.2 ± 0.1R⊕, 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.

Publishing year







Monthly Notices of the Royal Astronomical Society





Document type

Journal article


Oxford University Press


  • Planets and satellites: fundamental parameters
  • Stars: fundamental parameters
  • Stars: individual: K2-140
  • Stars: individual: K2-180
  • Techniques: photometric
  • Techniques: radial velocities




  • ISSN: 0035-8711