1999/06/14 by C. Ian Short, Peter H. Hauschildt, E. Baron · 1 citation
Chemistry · Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Atmosphere (unit) #Atmospheric models #Atmospheric sciences #Chemistry #Flux (metallurgy) #Gamma-ray bursts and supernovae #Ion #Ionization #Physics #Thermodynamic equilibrium #Thermodynamics #astro-ph
paper · pdf · doi:10.1086/307895
29 pages, 12 figures
arxiv created 1999/06/14 · openalex publication_date 1999/11/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We have used our PHOENIX multipurpose model atmosphere code to calculate atmospheric models that represent novae in the optically thick wind phases of their outburst. We have improved the treatment of non-local thermodynamic equilibrium (NLTE) effects by expanding the number of elements that are included in the calculations from 15 to 19 and the number of ionization stages from 36 to 87. The code can now treat a total of 10,713 levels and 102,646 lines in NLTE. Al, P, K, and Ni are included for the first time in the NLTE treatment, and most elements now have at least the lowest six ionization stages included in the NLTE calculation. We have investigated the effects of expanded NLTE treatment on the chemical concentration of astrophysically significant species in the atmosphere, the equilibrium structure of the atmosphere, and the emergent flux distribution. Although we have found general qualitative agreement with previous, more limited NLTE models, the expanded NLTE treatment leads to significantly different values for the size of many of the NLTE deviations. In particular, for the hottest model presented here ( T eff = 35,000 K), for which NLTE effects are largest, we find that the expanded NLTE treatment reduces the NLTE effects for these important variables: H I concentration, pressure structure, and emergent far-UV flux. Moreover, we find that the addition of new NLTE species may greatly affect the concentration of species that were already treated in NLTE, so that, generally, all species that contribute significantly to the e - reservoir or to the total opacity, or whose line spectrum overlaps or interlocks with that of a species of interest, must be treated in NLTE to ensure an accurate result for any particular species.