Temperature and density structure of the collapsing core of G10.6-0.4
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Abstract
The authors report on high-resolution aperture synthesis observations of the molecular gas surrounding the ultracompact H II region G 10.6-0.4 in the (J, K) = (1, 1) and (J, K) = (3, 3) inversion lines of NH3. Previous observations have suggested that the molecular gas around this source is gravitationally collapsing onto the central star or stars. The new data improve the identifications of the dynamical features. Maps of the NH3 rotational temperature and column density across the collapsing region show a hot, centrally condensed molecular core 0.1 pc in diameter with n(H2) = 4×106cm-3. The H II region embedded in the condensed core is heating the surrounding gas. The data indicate that a rotational motion is superposed on the infall velocity of the cloud. The velocity gradients are consistent with Keplerian rotation. The rotational velocity at 0.05 pc is about the same as the infall velocity at this radius indicating that the infalling gas may be spiraling in sharply toward the H II region.