# The Dissolution of Clusters: What Can We Learn from Nearby, UV-bright, Overluminous Field Stars?

## TL;DR

This study investigates a large sample of nearby UV-bright, young stars to understand their origins, kinematics, and potential as a previously unrecognized population of recently dispersed cluster members.

## Contribution

It identifies and analyzes a new population of young, UV-bright field stars with anomalous kinematics, challenging existing notions of cluster dissolution and star formation history.

## Key findings

- Less than 10% of stars are associated with known young moving groups.
- Most stars show anomalous kinematics compared to known groups.
- Many young stars are surprisingly X-ray faint.

## Abstract

The past two decades have seen dramatic progress in our knowledge of the population of young stars of age <200 Myr that lie within 150 pc of the Sun. These nearby, young stars, most of which are found in loose, comoving groups, provide the opportunity to explore (among many other things) the dissolution of stellar clusters and their diffusion into the field star population. In the age of Gaia, this potential can now be fully exploited. We have identified, and are now investigating, a sample of nearly 400 Galex UV-selected late-type (K and early-M) field stars with Gaia-based distances <120 pc and isochronal ages <=80 Myr (even if binaries). Only a small percentage (<10%) of stars among this (kinematically unbiased) sample can be confidently associated with established nearby, young moving groups (NYMGs). The majority display anomalous kinematics, relative to the known NYMGs. These stars may hence represent a previously unrecognized population of young stars that has recently mixed into the older field star population. We discuss the implications and caveats of such a hypothesis---including the intriguing fact that, in addition to their non-young-star-like kinematics, the majority of the UV-selected, isochronally young field stars within 50 pc appear surprisingly X-ray faint.