Constraining the age of young stellar clusters via the amplitude of photometric variability

TL;DR

This paper introduces a new method for estimating the ages of young stellar clusters by analyzing the amplitude of their stars' photometric variability, which decreases with age and can complement existing techniques.

Contribution

The study proposes a novel empirical approach to constrain the age of young stellar groups using photometric variability amplitude, validated across multiple clusters with Kepler K2 data.

Findings

Younger stars exhibit higher photometric variability than older stars with similar color and rotation period.

Photometric variability amplitude declines with age in low-mass stars, enabling age estimation.

Method can be combined with other techniques to improve age constraints for young stellar associations.

Abstract

Determination of stellar age is a crucial task in astrophysics research. Different methods are nowadays used either model dependent or based on calibrated empirical relations. The most reliable results are generally obtained when different methods are used in complementary way. We propose a new method for the age determination of young stellar associations and open clusters (ages < 125 Myr), which can allow to further constrain the age when used together with other methods. We explore the amplitude of the photometric variability in bins of color and rotation period of five young associations and clusters spanning an interval of ages from 1-3 Myr to 625 Myr (Taurus, rho Ophiuchi, Upper Scorpius, Pleiades, and Praesepe), which all have high-quality time-series photometry from Kepler K2 campaigns. In the low-mass regime, we find that stars with similar color and rotation period but different ages exhibit different amplitudes of their photometric variability, with younger stars showing a larger photometric variability than older stars. The decline of photometric variability amplitude versus age in stars with similar color and rotation period can be in principle calibrated and be adopted as an additional empirical relation to constrain the age of young associations and open clusters, provided that time-series photometry is available for their low-mass members.