BANYAN. V. A Systematic All-Sky Survey for New Very Late-Type Low-Mass Stars and Brown Dwarfs in Nearby Young Moving Groups

TL;DR

The paper introduces the BANYAN All-Sky Survey (BASS), a comprehensive catalog of 228 new late-type low-mass star and brown dwarf candidates in nearby young moving groups, aiding studies of stellar populations and exoplanet searches.

Contribution

It presents the first systematic all-sky survey for late-type low-mass stars and brown dwarfs in young moving groups, identifying new candidates and demonstrating signs of mass segregation.

Findings

Identified 228 new candidate members of YMGs, including 79 brown dwarfs.

Detected tentative signs of mass segregation in some YMGs.

Catalog will aid in studying the initial mass function and exoplanet direct imaging.

Abstract

We present the BANYAN All-Sky Survey (BASS) catalog, consisting of 228 new late-type (M4-L6) candidate members of nearby young moving groups (YMGs) with an expected false-positive rate of ~ 13%. This sample includes 79 new candidate young brown dwarfs and 22 planetary-mass objects. These candidates were identified through the first systematic all-sky survey for late-type low-mass stars and brown dwarfs in YMGs. We cross-matched the 2MASS and ALLWISE catalogs outside of the galactic plane to build a sample of 98 970 potential $\geq$ M5 dwarfs in the solar neighborhood and calculated their proper motions with typical precisions of 5-15 mas yr$^{-1}$. We selected highly probable candidate members of several YMGs from this sample using the Bayesian Analysis for Nearby Young AssociatioNs II tool (BANYAN II). We used the most probable statistical distances inferred from BANYAN II to estimate the spectral type and mass of these candidate YMG members. We used this unique sample to show tentative signs of mass segregation in the AB Doradus moving group and the Tucana-Horologium and Columba associations. The BASS sample has already been successful in identifying several new young brown dwarfs in earlier publications, and will be of great interest in studying the initial mass function of YMGs and for the search of exoplanets by direct imaging; the input sample of potential close-by $\geq$ M5 dwarfs will be useful to study the kinematics of low-mass stars and brown dwarfs and search for new proper motion pairs.