Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1779705 | New Astronomy | 2008 | 5 Pages |
Abstract
We investigate the variation of radio flux ratios and brightness temperatures in Galactic HII regions. These are compared to the results of a radiative transfer analysis, and shown to imply that large-scale density gradients must be relatively modest. Where the radial variation in density gradients is approximated by n ∝ r−β, then we determine that exponents β are ⩽1 (and probably ≪1). Similarly, it is probable that proportionate variations in density are relatively modest, and no greater (in the mean) than ∼102 or so. Such results are important for studies of the formation of such regions, and appear consistent with various hydrodynamical models.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Astronomy and Astrophysics
Authors
J.P. Phillips,