The Equilibria and Ultraviolet Spectra of h, he i, and he II in the Solar Atmosphere.
Abstract
The ionization equilibrium equations and source functions for the ions H, He I, and He ii are considered under conditions appropriate to the solar chromosphere. The equations are formulated in terms of both occupation numbers and bk parameters, in order to clarify their relationship to earlier work for H and He I. In the case of the ionization equations for H, somewhat more approximate forms are adopted from those appearing in earlier works, in order to illustrate more clearly the dominant transitions in the equilibrium The three ions considered here exhibit fundamental differences as well as many similarities in both the ionization equations and the source functions. A consideration of the ultraviolet spectra indicates that the central intensities in the Lyman-p lines are influenced mainly by the "local" value of Te near the region r = 1, whereas the central intensities of the Lyman-a lines are influenced by the distribution of T throughout a large range in r and cannot be described solely in terms of the "local' value of Te near r = 1. For this reason, observations of the Lyman-p profiles and fluxes by means of rockets and satellites become a much more valuable supplement to Lyman-a observations than had previously been supposed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- May 1960
- DOI:
- 10.1086/146883
- Bibcode:
- 1960ApJ...131..705A