SCUBA mapping of outer Galaxy protostellar candidates

¹ KOSMA, I. Physikalisches Institut, Universität zu Köln, Zülpicher Strasse 77, 50937 Cologne, Germany e-mail: bhaswati@tifr.res.in
² Department of Astronomy, University of Maryland, College Park, MD 20742, USA
³ SOFIA-USRA, NASA Ames Research Center, MS N211-3, Moffett Field, CA 94035, USA
⁴ Joint Astronomy Centre, 660 N. A'ohoku Place, University Park, Hilo, Hawaii 96720, USA

Received: 14 May 2007
Accepted: 16 July 2007

Abstract

Aims.We aim to study dust properties of massive star forming regions in the outer Galaxy, in a direction opposite to the Galactic center.

Methods.We present observations of six outer Galaxy point sources IRAS 01045+6505, 01420+6401, 05271+3059, 05345+3556, 20222+3541 and 20406+4555, taken with the Submillimeter Common-User Bolometer Array (SCUBA) on the James Clerk Maxwell Telescope (JCMT) at 450 and 850 μm. Single temperature greybody models are fitted to the Spectral Energy Distribution of the detected sub-mm cores to derive dust temperature, dust emissivity index and optical depth at 250 μm. The observed radial intensity profiles of the sub-mm cores were fitted with power laws to derive the indices describing the density distribution.

Results.At a resolution of 15´´ all six IRAS point sources show multiple emission peaks. Only four out of fourteen detected sub-mm cores show associated mid-infrared emission. For the sub-mm cores we derive dust temperatures of 32 ± 5 K and dust emissivity indices between 0.9 and 2.5. The density profiles of the sub-mm cores can be fitted by a single power law distribution with indices -1.5 ± 0.3, with most cores showing an index of -1.5. This is consistent with most observations of massive star forming regions and supports predictions of models of star formation which consider non-thermal support against gravitational collapse.