A Census of Stars and Disks in Corona Australis

TL;DR

This study provides a comprehensive census of young stars and their disks in Corona Australis, revealing two stellar populations with similar velocities and characterizing their disk properties using infrared data.

Contribution

It presents the first extensive catalog of members, spectroscopic classifications, and disk identifications in Corona Australis, clarifying its stellar populations and kinematic properties.

Findings

Catalog of 393 members with spectral classifications

Identification of two stellar populations with similar velocities

Detection of infrared excesses indicating circumstellar disks

Abstract

We have performed a census of the young stellar populations near the Corona Australis molecular cloud using photometric and kinematic data from several sources, particularly Gaia EDR3, and spectroscopy of hundreds of candidate members. We have compiled a catalog of 393 members of Corona Australis, (39 at >M6), 293 (36) of which are spectroscopically classified for the first time in this work. We find that Corona Australis can be described in terms of two stellar populations, a younger one (few Myr) that is partially embedded in the cloud (the Coronet Cluster) and an older one (~15 Myr) that surrounds and extends beyond the cloud (Upper Corona Australis). These populations exhibit similar space velocities, and we find no evidence for distinct kinematic populations in Corona Australis, in contrast to a recent study based on Gaia DR2. The distribution of spectral types in Corona Australis reaches a maximum at M5 (~0.15 M_sol), indicating that the IMF has a similar characteristic mass as other nearby star-forming regions. Finally, we have compiled mid-infrared photometry from the Wide-field Infrared Survey Explorer and the Spitzer Space Telescope for the members of Corona Australis and we have used those data to identify and classify their circumstellar disks. Excesses are detected for 122 stars, a third of which are reported for the first time in this work.