Companions to Kepler giant stars: A long-period eccentric sub-stellar companion to KIC 3526061 and a stellar companion to HD 187878

0568790 - ASÚ 2023 RIV FR eng J - Journal Article
Karjalainen, Marie - Karjalainen, Raine - Hatzes, A. - Lehmann, H. - Kervella, P. - Hekker, S. - Van Winckel, H. - Überlauer, J. - Vítková, M. - Skarka, Marek - Kabáth, Petr - Prins, S. - Tkachenko, A. - Cochran, W.D. - Jorissen, M.W.P.
Companions to Kepler giant stars: A long-period eccentric sub-stellar companion to KIC 3526061 and a stellar companion to HD 187878.
Astronomy & Astrophysics. Roč. 668, December (2022), č. článku A26. ISSN 0004-6361. E-ISSN 1432-0746
R&D Projects: GA MŠMT(CZ) LTT20015
Institutional support: RVO:67985815
Keywords : observational methods * radial velocities techniques * spectroscopic techniques
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 6.5, year: 2022
Method of publishing: Open access

We present the two systems from our planet search programme whose companions we were able to characterise: KIC 3526061 and HD 187878. We used precise stellar radial velocity measurements taken with four different echelle spectrographs to derive an orbital solution. We used Gaia astrometric measurements to obtain the inclination of the HD 187878 system and Kepler photometric observations to estimate the stellar mass and radius. We report the discovery of a sub-stellar companion and a stellar companion around two intermediate-mass red giant branch stars. KIC 3526061 b is most likely a brown dwarf with a minimum mass of 18.15 ± 0.44 MJupiter in a long-period eccentric orbit, with orbital period 3552−135+158 d and orbital eccentricity e = 0.85 ± 0.01. It is the most evolved system found having a sub-stellar companion with such a high eccentricity and wide separation. HD 187878 B has a minimum mass of 78.4 ± 2.0 MJupiter. Combining the spectroscopic orbital parameters with the astrometric proper motion anomaly, we derived an orbital inclination i = 9.8−0.6+0.4 deg, which corresponds to the companion's mass in the stellar regime of 0.51−0.02+0.04 M⊙.
Permanent Link: https://hdl.handle.net/11104/0340059