Abstract
The H2CO 6-cm line was observed with the VLA toward B335. The line is seen in absorption against the cosmic background radiation in a ring-shaped region centered on the infrared source. The data were analyzed with both LVG and microturbulent radiative transfer models. The two models agree qualitatively but differ quantitatively. The microturbulent model, which is physically more appropriate for this source, yields a best-fit power-law density profile of the form n proportional to 1/r exp alpha with alpha = 1.5-2.0, a temperature of 13-15 K, and an H2CO abundance of 2 x 10 to the -9th. Comparison of observations with theoretical models for low-mass star formation in the subcritical and superumbral regime (Shu et al., 1987) shows good agreement. The density estimates are considerably lower than previous density estimates from dust emission. By considering the effects of temperature and density gradients, it is possible to produce a better ageement between the estimates from dust and H2CO. 38 refs.
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