Planetary companion in K giant Sigma Persei

TL;DR

This paper reports the discovery of a planetary companion orbiting the K giant star sigma Persei, based on long-term radial velocity measurements indicating a likely exoplanet with specific orbital parameters.

Contribution

It presents the detection of a new exoplanet candidate around a K giant star using high-precision RV data, expanding knowledge of planets around evolved stars.

Findings

Detected a periodic RV variation of ~580 days.

Estimated planetary mass of approximately 6.5 Jupiter masses.

Orbital semi-major axis of about 1.8 AU with moderate eccentricity.

Abstract

We report the detection of an exoplanet candidate in orbit around sigma Persei from a radial velocity (RV) survey. The system exhibits periodic RV variations of 579.8 +/- 2.4 days. The purpose of the survey is to search for low-amplitude and long-period RV variations in giants and examine the origin of the variations using the fiber-fed Bohyunsan Observatory Echelle Spectrograph installed at the 1.8-m telescope of Bohyunsan Optical Astronomy Observatory in Korea. We present high-accuracy RV measurements of sigma Per made from December 2003 to January 2014. We argue that the RV variations are not related to the surface inhomogeneities but instead a Keplerian motion of the planetary companion is the most likely explanation. Assuming a stellar mass of 2.25 +/- 0.5 M_Sun, we obtain a minimum planetary companion mass of 6.5 +/- 1.0 M_Jup, with an orbital semi-major axis of 1.8 +/- 0.1 AU, and an eccentricity of 0.3 +/- 0.1 around sigma Per.