Massive Multispecies, Multilevel Non‐LTE Model Atmospheres for Novae in Outburst

We have used our PHOENIX multi-purpose model atmosphere code to calculateatmospheric models that represent novae in the optically thick wind phases oftheir outburst. We have improved the treatment of NLTE effects by expanding thenumber of elements that are included in the calculations from 15 to 19, and thenumber of ionization stages from 36 to 87. The code can now treat a total of10713 levels and 102646 lines in NLTE. Aluminum, P, K, and Ni are included forthe first time in the NLTE treatment and most elements now have at least thelowest six ionization stages included in the NLTE calculation. We haveinvestigated the effects of expanded NLTE treatment on the chemicalconcentration of astrophysically significant species in the atmosphere, theequilibrium structure of the atmosphere, and the emergent flux distribution.Although we have found general qualitative agreement with previous, morelimited NLTE models, the expanded NLTE treatment leads to significantlydifferent values for the size of many of the NLTE deviations. In particular,for the hottest model presented here (effective temperature of 35000 K), forwhich NLTE effects are largest, we find that the expanded NLTE treatmentreduces the NLTE effects for these important variables: neutral Hydrogenconcentration, pressure structure, and emergent far UV flux. Moreover, we findthat the addition of new NLTE species may greatly affect the concentration ofspecies that were already treated in NLTE, so that, generally, all species thatcontribute significantly to the electron reservoir or to the total opacity, orwhose line spectrum overlaps or interlocks with that of a species of interest,must be treated in NLTE to insure an accurate result for any particularspecies.Comment: 29 pages, 12 figure