A Close-in Planet Orbiting Giant Star HD 167768
Huan-Yu Teng, Bun'ei Sato, Masanobu Kunitomo, Takuya Takarada, Masashi Omiya, Hiroki Harakawa, Guang-Yao Xiao, Yu-Juan Liu, Hideyuki Izumiura, Eiji Kambe, Michitoshi Yoshida, Yoichi Itoh, Hiroyasu Ando, Eiichiro Kokubo, Ida Shigeru
November, 2022
Publication
Publications of the Astronomical Society of Japan
Abstract
We report the detection of a giant planet orbiting a G-type giant star HD 167768 from radial velocity measurements using HIgh Dispersion Echelle Spectrograph (HIDES) at Okayama Astrophysical Observatory (OAO).
HD 167768 has a mass of 1.08+0.14−0.12 M⊙, a radius of 9.70+0.25−0.25 R⊙, a metallicity of [Fe/H] = −0.67+0.09−0.08, and a surface gravity of logg=2.50+0.06−0.06.
The planet orbiting the star is a warm Jupiter, having a period of 20.6532+0.0032−0.0032 d, a minimum mass of 0.85+0.12−0.11 MJ, and an orbital semimajor axis of 0.1512+0.0058−0.0063 au.
The planet has one of the shortest orbital periods among those ever found around deeply evolved stars (logg<3.5cgs) using radial velocity methods.
The equilibrium temperature of the planet is 1874 K, as high as a hot Jupiter.
The radial velocities show two additional regular variations at 41 d and 95 d, suggesting the possibility of outer companions in the system.
Follow-up monitoring will enable validation of the periodicity.
We also calculated the orbital evolution of HD 167768 b and found that the planet will be engulfed within 0.15 Gyr.
[Teng et al. (2023a, PASJ)]