Departures from LTE in the Atmosphere of an A0 Star.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Departures from LTE in the Atmosphere of an A0 Star. Lecar, Myron Abstract Two model atmospheres have been constructed for an A0 star in radiative equilibrium, which maintain constancy of the flux to a part in 10~ for T~l and to a few parts in 10~ for larger i. The composition was pure hydrogen; the effective temperature was 1040K and the gravitational accelerations were 10~ and 10~. These models were based on the assumption of LTE. The resultant radiation fields and densities were then used to calculate the steady state atomic populations. The steady state populations differed from the LTE populations by as much as a factor of 2 at the optical depths where the lines were still transparent, but were essentially in LTE (to a fraction of a percent) at the depth where the continuous flux was formed. Thus the emergent continuous flux showed no departures from LTE. The emergent flux in the center of the resonance lines, however, was depressed by 30-40% as a result of departures from LTE. This effect was progressively less pronounced for the weaker lines. Publication: The Astronomical Journal Pub Date: 1963 DOI: 10.1086/109023 Bibcode: 1963AJ.....68Q..77L full text sources ADS |