A Close-in Planet Orbiting Giant Star HD 167768

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 $1.08_{-0.12}^{+0.14}{M}_{\odot }$, a radius of $9.70_{-0.25}^{+0.25}{R}_{\odot }$, a metallicity of $[Fe/H]=-0.67_{-0.08}^{+0.09}$, and a surface gravity of $\log g=2.50_{-0.06}^{+0.06}$. The planet orbiting the star is a warm Jupiter, having a period of $20.6532_{-0.0032}^{+0.0032}\mathrm{d}$, a minimum mass of $0.85_{-0.11}^{+0.12}{M}_{\mathrm{J}}$, and an orbital semimajor axis of $0.1512_{-0.0063}^{+0.0058}\mathrm{au}$. The planet has one of the shortest orbital periods among those ever found around deeply evolved stars ($\log g<3.5$) using radial velocity methods. The equilibrium temperature of the planet is $1874\mathrm{K}$, as high as a hot Jupiter. The radial velocities show two additional regular variations at $41\mathrm{d}$ and $95\mathrm{d}$, 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.

Accepted by Publications of the Astronomical Society of Japan, 9 pages, 7 figures, 2 tables

References in corpus (22)

• Array Programming with NumPy
• The Gaia mission
• Modules for Experiments in Stellar Astrophysics (MESA)
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• Gaia Early Data Release 3: The astrometric solution
• Assessing statistical significance of periodogram peaks
• Retired A Stars and Their Companions: Exoplanets Orbiting Three Intermediate-Mass Subgiants
• Hot Jupiters and Cool Stars
• Planet Engulfment by ~1.5-3 Solar-Mass Red Giants
• Kepler-432: a red giant interacting with one of its two long period giant planets
• Seeing double with K2: Testing re-inflation with two remarkably similar planets around red giant branch stars
• Kepler-432 b: a massive planet in a highly eccentric orbit transiting a red giant
• Bisectors of the cross-correlation function applied to stellar spectra. Discriminating stellar activity, oscillations and planets
• Giant planet occurrence within 0.2 AU of low-luminosity red giant branch stars with K2
• The TESS-Keck Survey II: An Ultra-Short Period Rocky Planet and its Siblings Transiting the Galactic Thick-Disk Star TOI-561
• Radial velocity confirmation of Kepler-91 b. Additional evidence of its planetary nature using the Calar Alto/CAFE instrument
• TESS Giants Transiting Giants II: The hottest Jupiters orbiting evolved stars
• A planetary system and a highly eccentric brown dwarf around the giant stars HIP67851 and HIP97233
• Precise Radial Velocity Measurements for Kepler Giants Hosting Planetary Candidates: Kepler-91 and KOI-1894
• Exoplanets in the Galactic context: Planet occurrence rates in the thin disk, thick disk and stellar halo of Kepler stars
• Regular Radial Velocity Variations in Nine G- and K-type Giant Stars: Eight Planets and One Planet Candidate
• TOI-1296b and TOI-1298b observed with TESS and SOPHIE: Two hot Saturn-mass exoplanets with different densities around metal-rich stars

Cited by in corpus (1)

• Precise radial velocities of giant stars -- XVII. Distinguishing planets from intrinsically induced radial velocity signals in evolved stars