A survey of TiO{\lambda}567 nm absorption in solar-type stars

TL;DR

This paper introduces a new TiO absorption-based color index to measure long-term stellar activity variations in solar-type stars, revealing activity cycles ranging from 2 to 17 years.

Contribution

It applies a novel TiO absorption index to a large star sample, providing insights into long-term stellar activity patterns.

Findings

Detected activity cycles from 2 to 17 years.

Established the statistical properties of the TiO index.

Demonstrated the index's effectiveness in monitoring stellar activity.

Abstract

Molecular absorption bands are estimators of stellar activity and spot cycles on magnetically active stars. We have previously introduced a new color index that compare absorption strength of the titanium oxide (TiO) at 567 nm with nearby continuum. In this paper we implement this index to measure long-term activity variations and the statistical properties of the index in a sample of 302 solar-type stars from the HARPS planet search program. The results indicate a pattern of change in star's activity, covers a range of periods from 2 years up to 17 years.