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CO observations of spiral structure and the lifetime of giant molecular clouds

Published online by Cambridge University Press:  14 August 2015

N. Z. Scoville ,
P. M. Solomon  and
D. B. Sanders
N. Z. Scoville
Affiliation:
Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts
P. M. Solomon
Affiliation:
Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts
D. B. Sanders
Affiliation:
Space Sciences Departmentm, State University of New York, Stony Brook, New York

Extract

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Observations of CO emission at ℓ=0 to 70°, |b| ≤ 1° are analyzed to give a map of the molecular cloud distribution in the galaxy as viewed from the galactic pole. From the fact that this distribution shows no obvious spiral pattern we conclude that the giant molecular clouds sampled in the CO line are situated in both arm and interarm regions and they must last more than 108 years. A similar age estimate is deduced from the large mass fraction of H2 in the interstellar medium in the interior of the galaxy. An implication of this longevity is that the great masses of these clouds may be accumulated through cloud-cloud collisions of originally smaller clouds.

Type
V. PHYSICAL PROPERTIES OF THE INTERSTELLAR MEDIUM
Information
Symposium - International Astronomical Union , Volume 84: The Large-Scale Characteristics of the Galaxy , 1979 , pp. 277 - 283
Copyright
Copyright © Reidel 1979 

References

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