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Astron. Astrophys. 336, 309-314 (1998)

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5. Summary

A plausible explanation for the anomalously widespread emission of CS compared with NH3 in low-mass star-forming regions is the formation (in the collapse process) of many clumps of dense gas, only some of which go on to form stars or at any rate persist for a long enough time to be visible in `late-time' molecules such as NH3, but all of which may be observable in `early-time' molecules such as CS. Here, models of this collapse process are used to predict which other molecules will fall into each of the CS and NH3 families, and which will be suitable for study at the appropriate resolution, if they have not already been mapped. HCN, H2CO, H2CS, C3N, HC3N, and C2H are found to fall into the CS family, whilst HCO+, SO, NO, OH, N2H+ and OCN are in the ammonia family. The reliability of the neutral-neutral chemistry that is predominantly responsible for their the formation is also considered.

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© European Southern Observatory (ESO) 1998

Online publication: July 7, 1998