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Cold HI Gas in the Region of the Giant Molecular Cloud Near M17

Published online by Cambridge University Press:  14 August 2015

Fumio Sato
Affiliation:
1Chiba Prefecture Education Center, Katsuragi-2, Chiba, Japan
Yasuo Fukui
Affiliation:
2Tokyo Astronomical Observatory, Mitaka, Tokyo, Japan
Tetsuo Hasegawa
Affiliation:
3Department of Astronomy, University of Tokyo, Tokyo, Japan

Extract

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Sato and Fukui (1978, hereafter SF) studied the HI 21-cm line in the giant molecular cloud near M17 and showed that the self-absorption of the 21-cm line is a useful tool for probing star-forming clouds. The giant molecular cloud at V(LSR) ∼ 20 km s-1 has been found to extend 4° (∼170 pc) southwest of M17 (Elmegreen et al. 1979). To gain a better knowledge of its physical conditions, we used the data from the Maryland-Green Bank Survey (Westerhout 1973) to examine the self-absorption features of the 21-cm line in and around the whole molecular cloud except the two fragments adjoining M17. The HI profiles at every in galactic latitude and longitude in the region were analyzed in almost the same manner as in SF by assuming that the spin temperature of the cold HI gas is equal to 20 K. The distance was taken to be 2.5 kpc.

Type
Research Article
Copyright
Copyright © Reidel 1980 

References

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