The prevalence of neutral gas in massive post-main-sequence nebulae

Phillips, J. P.; Mampaso, A.
Bibliographical reference

IN: The physics and chemistry of interstellar molecular clouds - mm and sub-mm observations in astrophysics; Proceedings of the Symposium, Zermatt, Switzerland, Sept. 22-25, 1988 (A90-33833 14-90). Berlin and New York, Springer-Verlag, 1989, p. 100-103.

Advertised on:
1989
Number of authors
2
IAC number of authors
0
Citations
0
Refereed citations
0
Description
Results are reported from a CO (J = 2-1) survey of nine type I nebulae using the 12-m NRAO antenna at KPNO; the data are presented in tables, graphs, and contour maps and briefly characterized. Three of the nebulae are found to have significant CO emission, with evidence of (1) dissociated molecular envelopes, (2) complete ionization of the gas by the central-star radiation field, and (3) extremely heterogeneous and clumped neutral zones. The quenching of the observed CO temperatures is tentatively attributed to the large H I velocity gradients (in excess of 100 km/sec pc) typical of such sources, and it is inferred that further observations at higher sensitivity could produce many more detections.