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The galactic density wave, molecular clouds and star formation

Published online by Cambridge University Press:  14 August 2015

Frank N. Bash
Frank N. Bash*
Affiliation:
Astronomy Department, University of Texas Austin, Texas 78712, USA

Abstract

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A model has been devised for the orbits of molecular clouds in the Galaxy. The molecular clouds are assumed to be launched from the two-armed spiral-shock wave, to orbit in the Galaxy like ballistic particles with gravitational perturbations due to the density-wave spiral-potential and each cloud is assumed to produce an identical cluster of stars. A comparison of the model with observations suggests that each cloud radiates detectable 12C160 (J = 1 → 0) spectral line radiation from birth to an age of 30 million years and that stars are seen in the cloud 15 million years after its birth. The model has been tested by comparing its predicted velocity-longitude diagram for CO against the observed one for the Galaxy and by comparing the model's predicted surface brightness in the UBV photo metric bands against observed surface photometry for Sb and Sc galaxies.

Type
III. SPIRAL STRUCTURE
Information
Symposium - International Astronomical Union , Volume 84: The Large-Scale Characteristics of the Galaxy , 1979 , pp. 165 - 172
Copyright
Copyright © Reidel 1979 

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