LABOCA mapping of the infrared dark cloud MSXDC G304.74+01.32
  Infrared dark clouds (IRDCs) likely represent very early stages of high-mass
star/star cluster formation. In this study, we aim to determine the physical
properties and spatial distribution of dense clumps in the IRDC MSXDC
G304.74+01.32 (G304.74), and bring these characteristics into relation to
theories concerning the origin of IRDCs and their fragmentation into clumps and
star-forming cores. G304.74 was mapped in the 870 $\mu$m dust continuum with
the LABOCA bolometer on APEX. Archival MSX and IRAS infrared data were used to
study the nature and properties of the submillimetre clumps within the cloud.
There are 8 clumps within G304.74 which are not associated with mid-infrared
(MIR) emission. Some of them are candidates for being/harbouring high-mass
starless cores (HMSCs). We compared the clump masses and their spatial
distribution in G304.74 with those in several other recently studied IRDCs.
There is a high likelihood that the clump mass distributions in G304.74 and in
several other IRDCs represent the samples of the same parent distribution. In
most cases the spatial distributions of clumps in IRDCs do not deviate
significantly from random distributions. This is consistent with the idea that
the origin of IRDCs, and their further sub-fragmentation down to scales of
clumps is caused by supersonic turbulence in accordance with results from giant
molecular clouds.
