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A kinematically unbiased, all-sky search for nearby, young, low-mass stars

A kinematically unbiased, all-sky search for nearby, young, low-mass stars Thumbnail


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. Here, we exploit the combination of astrometric and photometric data from {\it Gaia} and photometric data from GALEX (UV) and 2MASS (near-IR) in an attempt to identify additional nearby, young, late-type stars. Specifically, we present a sample of 146 GALEX UV-selected late-type (predominantly K-type) field stars with {\it Gaia}-based distances $< 125\,$pc (based on {\it Gaia} Data Release 1) that have isochronal ages $< 80\,$Myr even if equal-components binaries. We investigate the spectroscopic and kinematic properties of this sample. Despite their young isochronal ages, only $\sim 10$ per cent) of stars among this sample can be confidently associated with established nearby, young moving groups (MGs). These candidate MG members include 5 stars newly identified in this study. The vast majority of our sample of 146 nearby young star candidates have anomalous kinematics relative to the known MGs. These stars may hence represent a previously unrecognised 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.

Journal Article Type Article
Acceptance Date Oct 22, 2019
Online Publication Date Nov 5, 2019
Publication Date Jan 1, 2020
Publicly Available Date Mar 28, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 491
Issue 1
Pages 215-234
DOI https://doi.org/10.1093/mnras/stz3019
Keywords stars: kinematics and dynamics, stars: late-type, stars: pre-main-sequence, solar neighbourhood
Publisher URL https://doi.org/10.1093/mnras/stz3019

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