Supersoft X-ray Sources. Parameters of Stellar Atmospheres

Abstract

ROSAT spectra of 11 supersoft X-ray sources (RX J0439.8-6809, RX J0513.9-6951, RX J0527.8-6954, CAL 87, CAL 83, 1E 0035.4-7230, RX J0048.4-7332, 1E 0056.8-7154, RX J0019.8 +2156, RX J0925.7-4758, AG Draconis) are approximated with theoretical spectra obtained in LTE models for the atmospheres of hot white dwarfs with line blanketing. The confidence intervals of parameters derived from these approximations $ T_{\rm eff}$, $\log g$, $N_H$, and $R^2/d^2$ are determined. The results are compared with predictions for a model with stable/recurrent thermonuclear burning on the white-dwarf surface.