Detailed Non‐LTE Model Atmospheres for Novae during Outburst. I. New Theoretical Results

Abstract

We present new, detailed non-LTE (NLTE) calculations for model atmospheres of novae during outburst. This fully self-consistent NLTE treatment for a number of model atoms includes 3922 NLTE levels and 47,061 NLTE primary transitions. We discuss the implication of departures from LTE for the strengths of the lines in nova spectra. The new results show that our large set of NLTE lines constitutes the majority of the total line-blanketing opacity in nova atmospheres. Although we include LTE background lines, their effects are small on the model structures and on the synthetic spectra. We demonstrate that the assumption of LTE leads to incorrect synthetic spectra and that NLTE calculations are required for reliably modeling nova spectra. In addition, we show that detailed NLTE treatment for a number of ionization stages of iron changes the results of previous calculations and improves the fit to observed nova spectra.