OAO & BOES Results

In the past the Okayama Planet Search has provided several interesting planetary systems around evolved stars and it has been one of the earliest if not the first to obtain such results. Hence I’d propose to open a dedicated topic, otherwise feel free to submit separate posts for individual discoveries by Okayama Astrophysical Observatory.

The latest news…

A Close-in Planet Orbiting Giant Star HD 167768

Quote :

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+0.14−0.12M⊙, a radius of 9.70+0.25−0.25R⊙, 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<3.5) 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.

A search for exoplanets around north circumpolar stars. VII. Detection of planetary companion orbiting the largest host star HD 18438
https://arxiv.org/abs/2303.08357

Substellar companion to an M giant star (in turn binary).

Long-period radial velocity variations of nine M red giants: The detection of sub-stellar companions around HD 6860 and HD 112300
https://arxiv.org/abs/2307.15897

Better known as Beta Andromedae and Delta Virginis respectively, two notable bright stars.

Confirmed and putative additional planets in K giant star systems

Revisiting Planetary Systems in Okayama Planet Search Program: A new long-period planet, RV astrometry joint analysis, and multiplicity-metallicity trend around evolved stars
https://arxiv.org/abs/2308.05343