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

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)1807-1823
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Volume482
Issue number2
DOIs
StatePublished - Jan 11 2019

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

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

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