Interferometric [TSUP]13[/TSUP]CO Observations of the Cometary Bright-rimmed Cloud 37 in IC 1396: Evidence for Collapse Phase of Radiation-driven Implosion?

Abstract

Interferometric observations of the cometary bright-rimmed cloud BRC 37 (GN 21.38.9) located at the periphery of the H II region IC 1396 were made with the Nobeyama Millimeter Array in the 13CO (J = 1-0) transition. Although the global distribution of the molecular gas is consistent with the previous single-dish results, our high-resolution data clearly show small-scale structures with blueshifted velocity components corresponding to two clear tails stretching from the globule head in the opposite direction toward the exciting star of IC 1396. The elongation direction of these tails and other circumstances suggest an interaction with the UV radiation from the exciting star of IC 1396. The position-velocity diagram along the cloud axis shows a velocity pattern which may be explained by the collapsing gas motion. The morphology as well as the position-velocity diagram seems to be in agreement with the collapse phase of the recent two-dimensional simulations of the radiation-driven implosion of the neutral globule due to UV radiation from OB stars.