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

TL;DR

This study analyzes gas, dust, and star formation in the RCW 106 molecular cloud complex, revealing it as a highly active star-forming region undergoing a ministarburst, with detailed measurements of star formation rates and gas properties.

Contribution

First detailed multi-wavelength analysis of RCW 106, quantifying its star formation activity and confirming it as a ministarburst region in the Milky Way.

Findings

RCW 106 is a highly active star-forming complex with SFRs above ministarburst threshold.

The complex is undergoing a recent burst of star formation, with past and future SFR estimates.

It provides a nearby laboratory for studying massive star formation and high-redshift starburst physics.

Abstract

We report here a study of gas, dust and star formation rates (SFRs) in the molecular cloud complexes (MCCs) surrounding the giant H$\,{\rm \scriptsize{II}}$ region RCW$\,$106 using $^{12}$CO and $^{13}$CO$\,$(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 $l=330^{\circ}$-$335^{\circ}$ and $b=-1^{\circ}$-$1^{\circ}$ into two main MCCs: the RCW$\,$106 (V$_{\rm LSR} = -48\,$km$\,$s$^{-1}$) complex and the MCC331-90(V$_{\rm LSR} = -90\,$km$\,$s$^{-1}$) complex. While RCW$\,$106 (M$\sim 5.9\times 10^{6}\,$M$_{\odot}$) is located in the Scutum-Centaurus arm at a distance of 3.6$\,$kpc, MCC331-90 (M$\sim 2.8\times 10^{6}\,$M$_{\odot}$) is in the Norma arm at a distance of 5$\,$kpc. Their molecular gas mass surface densities are $\sim220$ and $\sim130\,$M$_{\odot}$ pc$^{-2}$, respectively. For RCW$\,$106 complex, using the 21$\,$cm continuum fluxes and dense clump counting, we obtain an immediate past ($\sim$-0.2$\,$Myr) and an immediate future ($\sim$+0.2$\,$Myr) SFRs of $0.25_{-0.023}^{+0.09}\,$M$_{\odot},{\rm yr}^{-1}$ and $0.12\pm0.1 \,$M$_{\odot}\,{\rm yr}^{-1}$. This results in an immediate past SFR density of $9.5_{-0.9}^{+3.4}\,$M$_{\odot}\,{\rm yr}^{-1}\,{\rm kpc}^{-2}$ and an immediate future SFR density of $4.8_{-3.8}^{+3.8}\,$M$_{\odot}\,{\rm yr}^{-1}\,{\rm kpc}^{-2}$. 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.