HD 89345: A bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2
Journal article, 2018
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+0.04M⊙and 1.657-0.004+0.020R⊙, respectively. The star appears to have recently left the main sequence, based on the inferred age, 9.4-1.3+0.4Gyr, 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.
Planets and satellites: formation
Asteroseismology
Planets and satellites: fundamental parameters
Planets and satellites: composition
Author
Vincent Van Eylen
Leiden University
Fei Dai
Princeton University
Massachusetts Institute of Technology (MIT)
S. Mathur
Instituto de Astrofísica de Canarias
University of La Laguna
D. Gandolfi
University of Turin
Simon Albrecht
Aarhus University
Malcolm Fridlund
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Leiden University
R. A. García
University Paris-Saclay
The French Alternative Energies and Atomic Energy Commission (CEA)
E. W. Guenther
Thüringer Landessternwarte Tautenburg
M. Hjorth
Aarhus University
A.B. Justesen
Aarhus University
J.H. Livingston
University of Tokyo
M. N. Lund
Aarhus University
F. Pérez Hernández
University of La Laguna
Instituto de Astrofísica de Canarias
J. Prieto-Arranz
University of La Laguna
Instituto de Astrofísica de Canarias
C. Regulo
University of La Laguna
Instituto de Astrofísica de Canarias
L. Bugnet
The French Alternative Energies and Atomic Energy Commission (CEA)
University Paris-Saclay
M.E. Everett
National Optical Astronomy Observatory
T. Hirano
Tokyo Institute of Technology
David Nespral
Instituto de Astrofísica de Canarias
University of La Laguna
G. Nowak
University of La Laguna
Instituto de Astrofísica de Canarias
E. Palle
University of La Laguna
Instituto de Astrofísica de Canarias
V. Silva Aguirre
Aarhus University
T. Trifonov
Max Planck Society
J. N. Winn
Princeton University
O. Barragán
University of Turin
P. G. Beck
Instituto de Astrofísica de Canarias
University of La Laguna
W. J. Chaplin
Aarhus University
University of Birmingham
William D. Cochran
The University of Texas at Austin
Szilard Csizmadia
German Aerospace Center (DLR)
H. Deeg
Instituto de Astrofísica de Canarias
University of La Laguna
M. Endl
The University of Texas at Austin
P. Heeren
Heidelberg-Königstuhl State Observatory
S. Grziwa
University of Cologne
A. Hatzes
Thüringer Landessternwarte Tautenburg
D. Hidalgo
Instituto de Astrofísica de Canarias
University of La Laguna
Judith Korth
University of Cologne
S. Mathis
University Paris-Saclay
The French Alternative Energies and Atomic Energy Commission (CEA)
P. Montanés Rodríguez
University of La Laguna
Instituto de Astrofísica de Canarias
Norio Narita
National Institutes of Natural Sciences
University of Tokyo
Martin Pätzold
University of Cologne
Carina Persson
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
F. Rodler
European Southern Observatory Santiago
Alexis M. S. Smith
German Aerospace Center (DLR)
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 478 4 4866-4880Exoplanets from space – CHEOPS and PLATO, ESA’s next two projects
Swedish National Space Board (174/18), 2017-01-01 -- 2022-12-31.
Subject Categories
Meteorology and Atmospheric Sciences
Astronomy, Astrophysics and Cosmology
Bioinformatics (Computational Biology)
Infrastructure
Onsala Space Observatory
DOI
10.1093/mnras/sty1390