SCUBA imaging of high mass star formation regions

We present 450 and 850 mu m images of five ultracompact HII regions (G10.47 , G12.21, G13.87, G31.41 and G43.89) taken at 9 "/15 " resolution with SCUB A on the JCMT, and photometric measurements of the central sources at 1350 and 2000 mu m. We confirm that the sources have high submillimetre fluxes a s expected from their IRAS fluxes at 100 mu m and molecular line emission. Each submillimetre image peaks towards the UCHII regions. Three sources (G1 0.47, G12.21 and G31.41) have particularly strong central peaks. These peak ed sources, which can be easily identified from radial profiles, were previ ously identified from spectral line surveys as containing hot molecular cor es. The non-peaked sources G13.87 and G43.89 do not have hot molecular core s. Using the DUSTY radiative transfer code, we model both the spectral ener gy distributions and radial profiles of the sources using a combination of r(-3/2) density profile envelopes plus, for the peaked sources, compact hig h optical depth cores. Although previous modelling of the SED of UCHII regi ons has been achieved with constant density shells, we find that r(-3/2) de nsity profiles are necessary to fit the submm radial emission profiles of t hese sources. In agreement with previous modelling, we find that the inner radius of the dust shells is larger than would be expected from dust sublim ation; the physical mechanism for this is unknown. Two sources (G10.37 and G12.21) have additional peaks within the 2.5' SCUBA field of view which are not known to contain UCHII regions and may contain high mass protostars.