A Census of the Stellar Populations in the Sco-Cen Complex

TL;DR

This study uses Gaia EDR3 data to identify and analyze nearly 10,000 stellar members of the Sco-Cen complex, characterizing their initial mass functions, ages, and velocities with high completeness and low contamination.

Contribution

It provides the first comprehensive census of Sco-Cen members using Gaia data, including new estimates of intrinsic colors for young stars and brown dwarfs.

Findings

Nearly 10,000 members identified with high completeness.

Populations share similar initial mass functions peaking near M4--M5.

Contamination estimated below 1% in a cleaner sample.

Abstract

I have used high-precision photometry and astrometry from the early installment of the third data release of Gaia (EDR3) to perform a survey for members of the stellar populations within the Sco-Cen complex, which consist of Upper Sco, UCL/LCC, the V1062 Sco group, Ophiuchus, and Lupus. Among Gaia sources with sigma(pi)<1 mas, I have identified 10,509 candidate members of those populations. I have compiled previous measurements of spectral types, Li equivalent widths, and radial velocities for the candidates, which are available for 3169, 1420, and 1740 objects, respectively. In a subset of candidates selected to minimize field star contamination, I estimate that the contamination is <1% and the completeness is ~90% at spectral types of <=M6-M7 for the populations with low extinction (Upper Sco, V1062 Sco, UCL/LCC). I have used that cleaner sample to characterize the stellar populations in Sco-Cen in terms of their initial mass functions, ages, and space velocities. For instance, all of the populations in Sco-Cen have histograms of spectral types that peak near M4--M5, which indicates that they share similar characteristic masses for their initial mass functions (~0.15-0.2 Msun). After accounting for incompleteness, I estimate that the Sco-Cen complex contains nearly 10,000 members with masses above ~0.01 Msun. Finally, I also present new estimates for the intrinsic colors of young stars and brown dwarfs (<=20 Myr) in bands from Gaia EDR3, the Two Micron All Sky Survey, the Wide-field Infrared Survey Explorer, and the Spitzer Space Telescope.