A near-infrared survey of the entire R Corona Australis cloud

TL;DR

This study provides a comprehensive near-infrared survey of the R Corona Australis cloud, cataloging thousands of sources and analyzing their properties to understand star formation in this nearby molecular cloud.

Contribution

It presents the first deep, wide-area JHK band mosaic of the entire R CrA cloud, including a detailed catalog and analysis of the stellar content and dust properties.

Findings

Cataloged about 3500 near-infrared sources.

Identified sources with mm-excess likely embedded in the cloud.

Compared extinction from NIR data with dust emission at 1.2 mm.

Abstract

To understand low- to intermediate-mass star-formation in the nearby R CrA molecular cloud, we try to identify the stellar content that is accessible with near-infrared observations. We obtained a JHK band mosaic of 10 x 60 arcmin square covering the entire RCrA molecular cloud with unprecedented sensitivity. We present a catalogue of about 3500 near-infrared sources fainter than the saturation limit K = 10 mag, reaching K = 18mag. We analysed the extended sources by inspecting their morphology and point sources by means of colour-colour and colour-magnitude diagrams. Additionally, we compared the extinction inferred from the NIR data with the line-of-sight dust emission at 1.2 mm. Sources towards high dust emission but relatively low H-K show a projected mm-exces; these sources are either immediately surrounded by cold circumstellar material or, if too red to be a true foreground object, they are embedded in the front layer of the 1.2 mm emitting dust cloud. In both cases they are most likely associated with the cloud.