Radiative transfer modeling of radio-frequency spectral line data - Accretion onto G10.6 - 0.4

This paper describes a procedure for simulating spectral line images of three-dimensional molecular clouds. It is suggested that this technique can be useful in the more general problem of determining the three-dimensional structure of molecular clouds. The technique is demonstrated by comparing observed and simulated images of the accretion flow associated with high-mass star formation in the region G10.6 - 0.4. As a result of the comparison, the temperature, density, and velocity fields are described, and a vector map of the accretion flow direction and magnitude is presented. The results indicate that the molecular cloud core is strongly condensed and has approximately equal velocities in rotation and infall at its current evolutionary state. The rapid collapse and lack of rotational support suggests that significant angular momentum transfer is occurring over scales at least as large as those observed (0.5 pc). A milligauss magnetic field would have sufficient energy to supply the required braking torque of 10 to the 47th ergs.