New Methods for Determining the Ages of PMS Stars

TL;DR

This paper introduces three novel methods for estimating the ages of pre-main-sequence stars, including empirical isochrones, a gap-based measure, and tau-squared fitting, highlighting their potential and current limitations.

Contribution

It presents three new techniques for determining PMS star ages, offering a robust ordering, a promising distance-independent measure, and a comparison of different age estimates.

Findings

Empirical isochrones provide a reliable age ordering.

The radiative convective gap could serve as an age indicator.

Tau-squared fitting reveals a factor of two difference in age estimates.

Abstract

We present three new methods for determining the age of groups of pre-main-sequence stars. The first, creating empirical isochrones allows us to create a robust age ordering, but not to derive actual ages. The second, using the width of the gap in colour-magnitude space between the pre-main-sequence and main-sequence (the radiative convective gap) has promise as a distance and extinction independent measure of age, but is as yet uncalibrated. Finally we discuss tau-squared fitting of the main sequence as the stars approach the terminus of the main sequence. This method suggests that there is a factor two difference between these "nuclear" ages, and more conventional pre-main-sequence contraction ages.