Cold Dust in Hot Regions

Abstract

We mapped five massive star forming regions with the SCUBA-2 camera on the James Clerk Maxwell Telescope (JCMT). Temperature and column density maps are obtained from the SCUBA-2 450 and 850 $\mu$m images. Most of the dense clumps we find have central temperatures below 20 K with some as cold as 8 K, suggesting that they have no internal heating due to the presence of embedded protostars. This is surprising, because at the high densities inferred from these images and at these low temperatures such clumps should be unstable, collapsing to form stars and generating internal heating. The column densities at the clump centres exceed 10${}^{23}$ cm${}^{-2}$, and the derived peak visual extinction values are from 25-500 mag for $\beta$ = 1.5-2.5, indicating highly opaque centres. The observed cloud gas masses range from $\sim$ 10 to 10${}^3$ M${}_{\odot }$. The outer regions of the clumps follow an $r^{-2.36\pm 0.35}$ density distribution and this power-law structure is observed outside of typically 10${}^4$ AU. All these findings suggest that these clumps are high-mass starless clumps and most likely contain high-mass starless cores.

Accepted for publication in AJ

References in corpus (7)

• SCUBA-2: iterative map-making with the Sub-Millimetre User Reduction Facility
• The Balloon-borne Large Aperture Submillimeter Telescope: BLAST
• Submillimetre point sources from the Archeops experiment: Very Cold Clumps in the Galactic Plane
• Large Area Mapping at 850 Microns. V. Analysis of the Clump Distribution in the Orion A South Molecular Cloud
• The Structure of a Low-Metallicity Giant Molecular Cloud Complex
• The dust temperatures of the prestellar cores in the rho Oph main cloud and in other star forming regions: consequences for the core mass function
• Connecting the Dots: Analyzing Synthetic Observations of Star-Forming Clumps in Molecular Clouds

Cited by in corpus (4)

• The Eruption of the Candidate Young Star ASASSN-15qi
• Probing the physical conditions and star formation processes in the Galactic HII region S305
• Probing gas kinematics and PDR structure around O-type stars in Sh 2-305 HII region
• Dust Temperature Profiles in Dense Cores Associated With Massive Star-Forming Regions