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Molecular Clouds

Published online by Cambridge University Press:  14 August 2015

P. Thaddeus
P. Thaddeus*
Affiliation:
Goddard Institute for Space Studies, New York City

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To attempt to understand star formation without knowing the physical state of the dense interstellar molecular gas from which stars are made is an almost impossible task. Star formation has developed late as a branch of astrophysics largely for lack of observational data, and in particular, has lagged badly behind the study of the atomic and ionized components of the interstellar gas because spectroscopic techniques which work well at low density have an unfortunate tendency to fail when the density is high. Optical spectroscopy, which has been applied to the interstellar medium for over 70 years, has made little progress in regions of high density because of obscuration, and the same is true a fortiori of spacecraft spectroscopy in the UV; radio 21-cm and recombination line observations, although unhampered by obscuration, are unsatisfactory because the dense condensations are almost entirely molecular in composition.

Type
Research Article
Information
Symposium - International Astronomical Union , Volume 75: Star Formation , 1977 , pp. 37 - 54
Copyright
Copyright © Reidel 1977 

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