A Search for Exoplanets around Northern Circumpolar Stars. IV. Six Planet Candidates to the K Giants, HD 44385, HD 97619, HD 106574, HD 118904, HD 164428, and HD 202432

TL;DR

This paper reports the discovery of six long-period exoplanet candidates orbiting K-giant stars, identified through precise radial velocity measurements, contributing to understanding planet occurrence around intermediate-mass stars.

Contribution

The study presents six new exoplanet candidates around K-giant stars from the SENS survey, with detailed orbital parameters and an initial planet occurrence rate estimate.

Findings

Six new exoplanet candidates with periods 418-1065 days

Minimum masses range from 1.9 to 8.5 Jupiter masses

Approximate 8% planet occurrence rate in the survey

Abstract

We report the discovery of long-period radial velocity (RV) variations in six intermediate-mass K-giant stars using precise RV measurements. These discoveries are part of the Search for Exoplanets around Northern Circumpolar Stars (SENS) survey being conducted at the Bohyunsan Optical Astronomy Observatory. The nature of the RV variations was investigated by looking for photometric and line shape variations. We can find no variability with the RV period in these quantities and conclude that RV variations are most likely due to unseen sub-stellar companions. Orbital solutions for the six stars yield orbital periods in the range 418-1065 days and minimum masses in the range 1.9-8.5 MJ. These properties are typical on planets around intermediate-mass stars. Our SENS survey so far has about an 8% confirmed planet occurrence rate, and it will provide better statistics on planets around giant stars when the survey is completed.