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