Advertisement

Astrophysics and Space Science

, Volume 216, Issue 1–2, pp 153–154 | Cite as

Modelling the constancy of X

  • S. D. Taylor
  • D. A. Williams
  • T. W. Hartquist
Article
  • 26 Downloads

Abstract

Observations of the CO J=1-0 line are commonly used as a tracer for molecular material in clouds. The ratio of the H2 column density to the integrated intensity of this line,X, is often taken to be constant, despite theoretical and observational uncertainty. We have tried to identify how this ratio depends on cloud parameters, testing a simple theoretical argument suggesting its invariance with respect to density. The apparent constancy can be understood if clouds are clumpy on scales of Av ≈ 1-2 mag.

Key words

Chemistry Molecular Hydrogen Cloud Models 

Copyright information

© Kluwer Academic Publishers 1994

Authors and Affiliations

  • S. D. Taylor
    • 1
  • D. A. Williams
    • 1
  • T. W. Hartquist
    • 2
  1. 1.Department of MathematicsUMISTManchesterUK
  2. 2.Max Planck Institut für Extraterrestrische PhysikGarching bei MünchenGermany

Personalised recommendations