The Nitrogen Spectra of WN Stars: The WN6 “Standard” Star HD 192163 (WR136)

Abstract

Hitherto our quantitative analyses of WR spectra [2][5] have been based on pure-helium models [1][6]. Now we further improved our non-LTE calculations by including a complex model atom of nitrogen (90 energy levels, 351 line transitions; with low-temperature dielectronic recombination) into our model atmospheres in order to synthesize adequately the spectra of WN subtypes (Wessolowski et al., in preparation). Together with the nitrogen (the most important “metal” in WN atmospheres), we introduced an improved temperature structure into our model calculations [3], now accounting for non-grey radiative equilibrium instead of the grey approximation applied so far. Moreover we took into account the line overlap of the considered elements (here: helium, nitrogen) and also their blanketing effects on the continuous radiation field.