Analaysis of the HII region distribution in external galaxies. III. Global properties and the radial distribution.
In this paper we study the global properties of the counts of HII regions in spiral galaxies and the properties of their radial distributions. The total number of HII regions detected in a galaxy is a function mainly of its distance from us, its inclination, its luminosity, and its molecular gas content, although the dependence on this latter factor is derived from fewer galaxies. We find that the outer parts of the radial density distributions can be represented by exponentials, both for the global distribution and for the distributions corresponding to each of the Fourier components separately. The scalelengths corresponding to the HII region distribution correlate well with the scalelengths corresponding to the light distribution, but are systematically lower.
Astronomy and Astrophysics Supplement Series
- Pub Date:
- December 1993