2002ApJ...577..798D

We present the results of the first detailed millimeter and submillimeter molecular line survey of bright-rimmed clouds, observed at FCRAO in the CO (J=1⟶0), C¹⁸O (J=1⟶0), HCO⁺ (J=1⟶0), H¹³CO⁺ (J=1⟶0), and N₂H⁺ (J=1⟶0) transitions, and at the Heinrich Hertz Telescope in the CO (J=2⟶1), HCO⁺ (J=3⟶2), HCO⁺ (J=4⟶3), H¹³CO⁺ (J=3⟶2), and H¹³CO⁺ (J=4⟶3) molecular line transitions. The source list is composed of a selection of bright-rimmed clouds from the catalog of such objects compiled by Sugitani et al. We also present observations of three Bok globules done for comparison with the bright-rimmed clouds. We find that the appearance of the millimeter CO and HCO⁺ emission is dominated by the morphology of the shock front in the bright-rimmed clouds. The HCO⁺ (J=1⟶0) emission tends to trace the swept-up gas ridge and overdense regions, which may be triggered to collapse as a result of sequential star formation. Five of the seven bright-rimmed clouds we observe seem to have an outflow; however, only one shows the spectral line blue-asymmetric signature that is indicative of infall in the optically thick HCO⁺ emission. We also present evidence that in bright-rimmed clouds the nearby shock front may heat the core from outside-in, thereby washing out the normally observed line infall signatures seen in isolated star-forming regions. We find that the derived core masses of these bright-rimmed clouds are similar to other low- and intermediate-mass star-forming regions.