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Session 20 - Molecular Clouds, Dense Cores, and Protostars.
Display session, Monday, January 15
North Banquet Hall, Convention Center

[20.17] New Protostellar Collapse Candidates: An HCO^+ Survey of the Class 0 Sources

E. M. Gregersen, N. J. Evans II (UT-Austin), S. Zhou, M. Choi (Academia Sinica)

A new category of young stellar objects, the Class 0 sources, have been suggested as protostellar collapse candidates. We have observed 23 Class 0 sources in the HCO^+ J=4-3 and 3-2 lines. Nine sources have the correct spectral line asymmetry for infall in both lines. Three sources have the opposite asymmetry, while the rest have no significant asymmetry. One source, L1157, has a red asymmetry in HCO^+ J=4-3 and a blue asymmetry in J=3-2. The H^13CO^+ J=4-3 and 3-2 lines were also observed to find the velocity centroid of the gas. The bolometric temperature was calculated for 11 sources. Limits were calculated for five more sources. The mean bolometric temperatre of our sample, excluding IRAS 20050+2720, is 43\pm6 K. A Monte Carlo code was used to produce an evolutionary sequence of models of the HCO^+ J=4-3 and 3-2 lines in a collapsing cloud and to model the infall in L1527.

Program listing for Monday