Star-Forming Cores in Bok Globules

Previous abstract Next abstract

Session 49 -- Star Formation
Display presentation, Thursday, January 13, 9:30-6:45, Salons I/II Room (Crystal Gateway)

[49.02] Star-Forming Cores in Bok Globules

Y. Wang, N. J. Evans II (Univ. of Texas), S. Zhou (Univ. of Illinois), D. P. Clemens (Boston Univ.), J. Yun (Univ. of Lisbon)

Isolated Bok globules are well-suited for studying low-mass star formation due to their simple structure and relative isolation. We have carried out a study of isolated globules in an attempt to identify dense cores which are forming stars and to search for spectral evidence for infall in protostellar cores by using the FCRAO 14 m and the CSO 10.4 m telescopes.

A survey at the FCRAO in the CS J=2$\rightarrow$1 line toward 31 globules detected 15 dense cores; 8 of the detected cores have outflows and have IRAS point sources located within the FWHM extents of the CS emitting regions. The associated IRAS sources predominently have spectral energy distributions characteristic of young, embedded sources. We suggest that these dense cores with embedded sources are possible candidates for protostellar cores.

We have undertaken a survey in the C$^{18}$O J=2$\rightarrow$1 and the H$_{2}$CO 3$_{12} \rightarrow$2$_{11}$ lines toward the gloubules using the CSO to look for spectral signatures of infall. In quiescent cores, the C$^{18}$O line and the H$_{2}$CO line should have the same velocity centroid and similar line width. In collapsing cores, the H$_{2}$CO line, arising from inner, denser region which is expected to be free-falling onto the central protostar or accretion disk, should exhibit wider, more asymmetric, and blue-shifted profiles relative to the C$^{18}$O line. Our initial survey has identified four candidates for protostellar collapse with these signatures.

Thursday program listing