Etoile centrale et condition d'ionisation de l'enveloppe de la nova Delphini 1967

After correcting the observed flux of the forbidden lines for the supplementary reddening (due to the circumstellar envelope), we have recalculated the electron density and temperature of the envelope of the Nova. We have determined the temperature and radius of the Nova and obtained values of 1.03×10⁵ K, 1.15×10⁵ K and 1.21×10⁵ K for the temperature and values of 8.49×10¹⁰ cm, 4.32×10¹⁰ cm and 1.18×10¹⁰ cm for the radius of the Nova for 1968, 1969 and 1970, respectively. Using the temperature and radius of the Nova the electron density and temperature of the envelope and the degree of ionization, we have determined the optical depth of the envelope in the Lyman continuum, and found that it is of the order of 10 during the nebular stage.Considering the stratification of the envelope in different regions of ionization, we have determined the radius of the inner and outer edge and the electron temperature of every region. We found that the electron temperature of the inner part of the envelope is at least three times greater than that of the outer part. The variation of electron temperature as a function of the radius of the ionization region considered shows an abrupt increase of theT _e whenR/R _out(env) is between 0.44 and 0.54.