2015ApJ...806..201S

We report the results of the ¹²CO (J = 3-2) and HCO⁺ (J = 4-3) observations of the W40 H ii region with the Atacama Submillimeter Telescope Experiment (ASTE) 10 m telescope (HPBW ~= 22{#8243}) to search for molecular outflows and dense clumps. We found that the velocity field in the region is highly complex, consisting of at least four distinct velocity components at V_LSR~= 3, 5, 7, and 10 km/s. The ∼7 km/s component represents the systemic velocity of cold gas surrounding the entire region, and causes heavy absorption in the ¹²CO spectra over the velocity range 6 ≲ V_LSR≲ 9 km/s. The ∼5 and ∼10 km/s components exhibit high ¹²CO temperature (≳40 K) and are found mostly around the H ii region, suggesting that these components are likely to be tracing dense gas interacting with the expanding shell around the H ii region. Based on the ¹²CO data, we identified 13 regions of high velocity gas, which we interpret as candidate outflow lobes. Using the HCO⁺ data, we also identified six clumps and estimated their physical parameters. On the basis of the ASTE data and near-infrared images from 2MASS, we present an updated three-dimensional model of this region. In order to investigate molecular outflows in W40, the SiO (J = 1-0, v = 0) emission line and some other emission lines at 40 GHz were also observed with the 45 m telescope at the Nobeyama Radio Observatory, but they were not detected at the present sensitivity.