The PSU/TCfA Search for Planets Around Evolved Stars: Bisector Analysis of Activity of a Sample of Red Giants

TL;DR

This study uses bisector analysis of spectral lines to distinguish between planetary signals and stellar activity in red giants, aiding in accurate exoplanet detection around evolved stars.

Contribution

It introduces a method for analyzing stellar activity in red giants to differentiate between planetary signals and stellar phenomena.

Findings

Bisector analysis helps identify stellar activity as the cause of RV variations.

The method improves the reliability of exoplanet detection around evolved stars.

Application to two stars demonstrates the effectiveness of the approach.

Abstract

Searches for planets around evolved G-K subgiant and giant stars are essential for developing general understanding of planet formation and evolution of the planetary systems. Precise radial velocity (RV) measurements of giants have lead to the discovery of ten planets around such star. However, the long period radial velocity variations of red giants may also have other than planetary nature. Non-radial oscillations or rotational modulation due to starspots can also induce RV variations, thereby mimicking the gravitational influence of low-mass companions. In this work we present bisector analysis of five carefully selected lines for two stars from our survey.