Non‐LTE Model Atmospheres for Late‐Type Stars. II. Restricted Non‐LTE Calculations for a Solar‐like Atmosphere

Abstract

We test our knowledge of the atomic opacity in the solar UV spectrum. Using the atomic data compiled in the first paper in this series from modern, publicly available databases, we perform calculations that are compared with space-based observations of the Sun. At wavelengths longer than about 2600 Å, LTE modeling can reproduce quite closely the observed fluxes; uncertainties in the atomic line data account fully for the differences between calculated and observed fluxes. At shorter wavelengths, departures from LTE appear to be important, since our LTE and restricted non-LTE calculations differ. Analysis of visible/near-IR Na I and O I lines, two species that produce a negligible absorption in the UV, shows that observed departures from LTE for these species can be reproduced very accurately with restricted (fixed atmospheric structure) non-LTE calculations.