This study demonstrates a crucial difference between quiescent Bok globules and dark cloud cores. Seventeen small, quiescent Bok globules were probed for the molecular lines of NH_3 (J,K=1,1) and HC_3N (J=4->3) using the Haystack telescope. The sources have 3sigma integrated line intensity upper limits generally less than 0.1 K-km s(-1) . In terms of the reference source, TMC-2, this is less than about 10% of the brightness of the NH_3 (1,1) line, and less than about 30% of brightness of the HC_3N (4->3) line. A simple statistical equilibrium analysis indicates that chemical abundances of NH_3 and HC_3N in these globules are diminished by factors of 10 and 6, respectively, relative to dark cloud cores. Second, for plausible globule core sizes, densities are about 6 times smaller compared to those of dark cloud cores.
American Astronomical Society Meeting Abstracts #184
- Pub Date:
- May 1994