A Near-Infrared Imaging Survey of Coal Sack Globule 2

RACCA, G., GÓMEZ, M., & KENYON, S.

ASTRONOMICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2002 p. 2178 - 2184

0004-6256

We describe a near-infrared imaging survey of Globule 2 in the Coalsack. This Bok globule is the highest-density region of this southern hemisphere molecular cloud and is the most likely location for young stars in this complex. The survey is complete for K<14.0, H<14.5, and J<15.5, several magnitudes more sensitive than previous observations of this globule. From the large number of background stars, we derive an accurate near-infrared extinction law for the cloud. Our result, E(J-H)/E(H-K)=2.08+/-0.03, is significantly steeper than results for other southern clouds. We use the J-H/H-K color-color diagram to identify two potential young stars with K<14.0 in the region. We apply H-band star counts to derive the density profile of Coalsack Globule 2 and use a polytropic model to describe the internal structure of this small cloud. For a gas temperature T~15 K, this globule is moderately unstable.