A SUBMILLIMETER CONTINUUM STUDY OF S-140 L-1204 - THE DETECTION OF 3 NEW SUBMILLIMETER SOURCES AND A SELF-CONSISTENT MODEL FOR THE REGION/

We present submillimetre continuum observations of the L 1204/S 140 co mplex in broad bands centred at 450, 800 and 1100 mu m. The morphology of the region is similar at all three wavelengths, with the emitting region compact, about 90 arcsec in diameter, and centrally peaked arou nd the cloud core. Three new submillimetre continuum sources are obser ved which are not coincident with any previously known near or mid-inf rared Sources. We designate the sources S 140-SMM1-3. SMM1 is roughly coincident with a previously known NH3 clump and 2.7mm source, and nea r-IR reflection nebulosity from the surface of SMM2 has previously bee n seen. The three submillimetre continuum sources may be protostellar in nature, although it is not possible to determine whether they are g ravitationally bound, since virial mass estimates are disrupted by the presence of an energetic bipolar outflow. For this reason, earlier cl aims that the 2.7mm source in SMM1 is collapsing appear somewhat prema ture. The observation that SMM1 and SMM2 lie either side of the infrar ed sources, in a line roughly perpendicular to the direction of the bi polar outflow, imply they may be the remnants of a large-scale disk. C omparison of the continuum emission with previous high resolution CS, NH3 and CI observations provides evidence that, for the first time, de monstrates the photon-dominated region and outflow are intimately link ed. The only scenario that is able to explain all of the available mol ecular and atomic emission line data and our submillimetre continuum d ata, is one in which the outflow has expanded towards the edge of the molecular cloud and the edge of the blueshifted outflow lobe is now bo unded by the expanding HII region. The NH3 and continuum emission eman ate from the inner edge of the outflow lobe, shielded from the externa l UV field. A plot of the 800 mu m flux against N((CO)-O-18) implies t hat the dust/gas mass ratio is close to the canonical value (similar t o 1%) at the lower end of the observed extinction range (A(V) less tha n or equal to 70), but for the highest observed extinctions (A(V) =70- 100) the continuum flux density increases rapidly, implying a higher d ust/gas mass ratio is appropriate (similar to 2-5%), possibly indicati ng freeze-out of gas onto dust grains.