# The Elusive Majority of Young Moving Groups. I. Young Binaries and Lithium-Rich Stars in the Solar Neighborhood

## TL;DR

This study systematically identifies and characterizes young, active low-mass stars within 100 parsecs, revealing new members of known young moving groups and discovering numerous close binaries for future dynamical studies.

## Contribution

It provides a comprehensive all-sky survey of young, active low-mass stars near the Sun, including new members of young moving groups and a catalog of close binaries for mass measurements.

## Key findings

- 58 stars with strong lithium indicating ages 10-200 Myr
- Over 600 stars identified as potential young stars
- More than 200 new close binaries discovered

## Abstract

Young stars in the solar neighborhood serve as nearby probes of stellar evolution and represent promising targets to directly image self-luminous giant planets. We have carried out an all-sky search for late-type ($\approx$K7$-$M5) stars within 100 pc selected primarily on the basis of activity indicators from $GALEX$ and $ROSAT$. Approximately two thousand active and potentially young stars are identified, over 600 of which we have followed up with low-resolution optical spectroscopy and over 1000 with diffraction-limited imaging using Robo-AO at the Palomar 1.5-m telescope. Strong lithium is present in 58 stars, implying ages spanning $\approx$10$-$200 Myr. Most of these lithium-rich stars are new or previously known members of young moving groups including TWA, $\beta$ Pic, Tuc-Hor, Carina, Columba, Argus, AB Dor, Upper Centaurus Lupus, and Lower Centaurus Crux; the rest appear to be young low-mass stars without connections to established kinematic groups. Over 200 close binaries are identified down to 0.2$''$ $-$ the vast majority of which are new $-$ and will be valuable for dynamical mass measurements of young stars with continued orbit monitoring in the future.