Kagoshima galactic object survey with the Nobeyama 45-metre telescope by mapping in ammonia lines (KAGONMA): star formation feedback on dense molecular gas in the W33 complex

Abstract

ABSTRACT We present the results of NH3 (1,1), (2,2), and (3,3) and H2O maser simultaneous mapping observations toward the high-mass star-forming region W33 with the Nobeyama 45-m radio telescope. W33 has six dust clumps, one of which, W33 Main, is associated with a compact H ii region. To investigate star-forming activity feedback on its surroundings, the spatial distribution of the physical parameters was established. The distribution of the rotational temperature shows a systematic change from west to east in our observed region. The high-temperature region obtained in the region near W33 Main is consistent with interaction between the compact H ii region and the peripheral molecular gas. The size of the interaction area is estimated to be approximately 1.25 pc. NH3 absorption features are detected toward the centre of the H ii region. Interestingly, the absorption features were detected only in the NH3 (1,1) and (2,2) transitions, with no absorption feature seen in the (3,3) transition. These complex profiles in NH3 are difficult to explain by a simple model and may suggest that the gas distribution around the H ii region is highly complicated.