The Three-MM Ultimate Mopra Milky Way Survey II. Cloud and Star Formation Near the Filamentary Ministarburst RCW 106

Abstract

We report here a study of gas, dust and star formation rates (SFRs) in the molecular cloud complexes (MCCs) surrounding the giant HII region RCW106 using 12CO and 13CO(1-0) data from the Three- mm Ultimate Mopra Milky way Survey (ThrUMMS) and archival data. We separate the emission in the Galactic Plane around l = 330 -335 and b = ð€€€1 -1 into two main MCCs: the RCW106 (VLSR = ð€€€48kmsð€€€1) complex and the MCC331-90(VLSR = ð€€€90kmsð€€€1) complex. While RCW106 (M 5:9 106M ) is located in the Scutum-Centaurus arm at a distance of 3.6 kpc, MCC331-90 (M 2:8 106M ) is in the Norma arm at a distance of 5 kpc. Their molecular gas mass surface densities are 220 and 130M pcð€€€2, respectively. For RCW106 complex, using the 21 cm continuum

uxes and dense clump counting, we obtain an immediate past ( -0.2 Myr) and an immediate future ( +0.2 Myr) SFRs of 0:25+0:09 ð€€€0:023M ; yrð€€€1 and 0:12 0:1M yrð€€€1. This results in an immediate past SFR density of 9:5+3:4 ð€€€0:9M yrð€€€1 kpcð€€€2 and an immediate future SFR density of 4:8+3:8 ð€€€3:8M yrð€€€1 kpcð€€€2. As both SFRs in this cloud are higher than the ministarburst threshold, they must be undergoing a ministarburst event although burst peak has already passed. We conclude that this is one of the most active star forming complexes in the southern sky, ideal for further investigations of massive star formation and potentially shedding light on the physics of high-redshift starbursts