Dust and HCO+ Gas in the Star Forming Core W3-SE

Abstract

We report new results from CARMA observations of both continuum and HCO+(1-0) emission at 3.4 mm from W3-SE, a molecular core of intermediate mass, together with the continuum observations at 1.1 and 0.85/0.45 mm with the SMA and JCMT. A continuum emission core elongated from SE to NW (~10"), has been observed at the and further resolved into a double source with the SMA at 1.1 mm, with a separation of ~4". Together with the measurements from the Spitzer and MSX at mid-IR, we determined the SED of W3-SE and fit it with a thermal dust emission model, suggesting the presence of two dust components with different temperatures. The emission at mm/submm wavelengths is dominated by a major cold (~41 K) with a mass of ~65 Msun. In addition, there is a weaker hot component (~400 K) which accounts for emission in the mid-IR, suggesting that a small fraction of dust has been heated by newly formed stars. We also imaged the molecular core in the HCO+(1-0) line using CARMA at an angular resolution ~6". With the CARMA observations, we have verified the presence of a blue-dominated double peak profile toward this core. The line profile cannot be explained by infall alone. The broad velocity wings of the line profile suggest that other kinematics such as outflows within the central 6" of the core likely dominate the resulting spectrum. The kinematics of the sub-structures of this core suggest that the molecular gas outside the main component appears to be dominated by the bipolar outflow originated from the dust core with a dynamical age of >30000 yr. Our analysis, based on the observations at wavelengths from mm/submm to mid-IR suggests that the molecular core W3-SE hosts a group of newly formed young stars and protostars.