The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370
Journal article, 2017
We report on the discovery of a planetary companion candidate with a minimum mass M sin i = 4.6 +/- 1.0 M-Jupiter orbiting the K2 III giant star HD 175370 (KIC 007940959). This star was a target in our programme to search for planets around a sample of 95 giant stars observed with Kepler. This detection was made possible using precise stellar radial velocity measurements of HD 175370 taken over five years and four months using the coude echelle spectrograph of the 2-m Alfred Jensch Telescope and the fibre-fed echelle spectrograph High Efficiency and Resolution Mercator Echelle Spectrograph of the 1.2-m Mercator Telescope. Our radial velocity measurements reveal a periodic (349.5 +/- 4.5 d) variation with a semi-amplitude K = 133 +/- 25 ms(-1), superimposed on a long-term trend. A low-mass stellar companion with an orbital period of similar to 88 yr in a highly eccentric orbit and a planet in a Keplerian orbit with an eccentricity e = 0.22 are the most plausible explanation of the radial velocity variations. However, we cannot exclude the existence of stellar envelope pulsations as a cause for the low-amplitude radial velocity variations and only future continued monitoring of this system may answer this uncertainty. From Kepler photometry, we find that HD 175370 is most likely a low-mass red giant branch or asymptotic giant branch star.
planetary systems
stars: individual: HD 175370 (KIC 007940959)
techniques: radial velocities
methods: observational
techniques: spectroscopic
methods: data analysis
Author
M. Hrudkova
Isaac Newton Group
A. Hatzes
Thuringer Landessternwarte Tautenburg
R. Karjalainen
Isaac Newton Group
H. Lehmann
Thuringer Landessternwarte Tautenburg
S. Hekker
Aarhus Universitet
Max Planck Institut fur Sonnensystemforschung
M. Hartmann
Thuringer Landessternwarte Tautenburg
A. Tkachenko
KU Leuven
S. Prins
KU Leuven
H. van Winckel
KU Leuven
R. De Nutte
Royal Observatory of Belgium
L. Dumortier
Royal Observatory of Belgium
Y. Fremat
Royal Observatory of Belgium
H. Hensberge
Royal Observatory of Belgium
A. Jorissen
Université libre de Bruxelles (ULB)
P. Lampens
Royal Observatory of Belgium
M. Laverick
KU Leuven
Robin Lombaert
Chalmers, Earth and Space Sciences, Onsala Space Observatory
P. I. Papics
KU Leuven
G. Raskin
KU Leuven
A. Sodor
Royal Observatory of Belgium
Konkoly Observatory Hungarian Academy of Sciences
A. Thoul
Universite de Liege
Kavli Institute for Theoretical Physics
S. Van Eck
Université libre de Bruxelles (ULB)
C. Waelkens
KU Leuven
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 464 1 1018-1028Subject Categories (SSIF 2011)
Astronomy, Astrophysics and Cosmology
DOI
10.1093/mnras/stw2379