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Judith Korth



HD 89345 : A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2


  • V. Van Eylen
  • F. Dai
  • S. Mathur
  • D. Gandolfi
  • S. Albrecht
  • M. Fridlund
  • R. A. García
  • E. Guenther
  • M. Hjorth
  • A. B. Justesen
  • J. Livingston
  • M. N. Lund
  • F. Pérez Hernández
  • J. Prieto-Arranz
  • C. Regulo
  • L. Bugnet
  • M. E. Everett
  • T. Hirano
  • D. Nespral
  • G. Nowak
  • E. Palle
  • V. Silva Aguirre
  • T. Trifonov
  • J. N. Winn
  • O. Barragán
  • P. G. Beck
  • W. J. Chaplin
  • W. D. Cochran
  • S. Csizmadia
  • H. Deeg
  • M. Endl
  • P. Heeren
  • S. Grziwa
  • A. P. Hatzes
  • D. Hidalgo
  • J. Korth
  • S. Mathis
  • P. Montañes Rodriguez
  • N. Narita
  • M. Patzold
  • C. M. Persson
  • F. Rodler
  • A. M.S. Smith

Summary, in English

We report the discovery and characterization of HD 89345b (K2-234b; EPIC 248777106b), a Saturn-sized planet orbiting a slightly evolved star. HD 89345 is a bright star (V = 9.3 mag) observed by the K2 mission with 1 min time sampling. It exhibits solar-like oscillations. We conducted asteroseismology to determine the parameters of the star, finding themass and radius to be 1.12-0.01+0.04 M and 1.657 -0.004 +0.020 R, respectively. The star appears to have recently left the main sequence, based on the inferred age, 9.4-1.3+0.4 Gyr, and the non-detection of mixed modes. The star hosts a 'warm Saturn' (P = 11.8 d, Rp = 6.86 ± 0.14 R). Radial-velocity follow-up observations performed with the FIbre-fed Echelle Spectrograph, HARPS, and HARPS-N spectrographs show that the planet has a mass of 35.7 ± 3.3 M. The data also show that the planet's orbit is eccentric (e≈0.2). An investigation of the rotational splitting of the oscillation frequencies of the star yields no conclusive evidence on the stellar inclination angle. We further obtained Rossiter-McLaughlin observations, which result in a broad posterior of the stellar obliquity. The planet seems to confirm to the same patterns that have been observed for other sub-Saturns regarding planet mass and multiplicity, orbital eccentricity, and stellar metallicity.

Publishing year







Monthly Notices of the Royal Astronomical Society





Document type

Journal article


Oxford University Press


  • Asteroseismology
  • Planets and satellites: composition
  • Planets and satellites: formation
  • Planets and satellites: fundamental parameters




  • ISSN: 0035-8711