The compact molecular core toward G34.3 + 0.2 - VLA observations in the (2,2) and (3,3) lines of ammonia

Abstract

The VLA was used to map the NH3 emission in the lines of the (J,K) = (2,2) and (J,K) = (3,3) inversion transitions toward the warm molecular cloud associated with the compact H II region G34.3 + 0.2. The main HF line of the (2,2) inversion transition is detected in absorption in the western half of the source and in emission in the eastern half. The main HF line of the (3,3) inversion transition is detected in emission over the whole source. The HF satellite lines of the (2,2) and (2,3) inversion transitions are detected only in emission. A molecular cloud exhibits a core-halo structure in which the emission from the HF satellite lines arise from an ultracompact region near the center of the cloud and the emission in the main HF component of the (3,3) transition arises from a disklike structure. The rotational temperature increases from about 70 K near the edges of the core to about 185 K at the position of the ultracompact molecular core. The hydrogen molecular density in the ultracompact core is about 7 x 10 to the 7th/cu cm.