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The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370

Hrudkova, M. and Hatzes, A. and Karjalainen, E. and Lehmann, H. and Hekker, S. and Hartmann, M. and Tkachenko, A. and Prins, S. and Van Winckel, H. and De Nutte, R. and Dumortier, L. and Frémat, Yves and Hensberge, H. and Jorissen, A. and Lampens, Patricia and Laverick, M. and Lombaert, R. and Pápics, P.I. and Raskin, G. and Sódor, Ádám and Thoul, A. and Van Eck, S. and Waelkens, C. (2016) The discovery of a planetary candidate around the evolved low-mass Kepler giant star HD 175370. Monthly Notices of the Royal Astronomical Society.

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Abstract

We report on the discovery of a planetary companion candidate with a minimum mass M sin i = 4.6 ± 1.0 MJupiter orbiting the K2 III giant star HD 175370 (KIC 007940959). This star was a target in our program 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 coudé echelle spectrograph of the 2-m Alfred Jensch Telescope and the fibre-fed echelle spectrograph HERMES of the 1.2-m Mercator Telescope. Our radial velocity measurements reveal a periodic (349.5 ± 4.5 days) 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 ˜88 years 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.

Item Type: Article
Subjects: Q Science / természettudomány > QB Astronomy, Astrophysics / csillagászat, asztrofizika
Depositing User: Dr. Ádám Sódor
Date Deposited: 05 Oct 2016 07:11
Last Modified: 05 Oct 2016 07:11
URI: http://real.mtak.hu/id/eprint/41439

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