SIMBAD references

Using the coude spectrograph of the NAO 2m telescope at the Rhodope Mountains, Bulgaria, 9 spectra in the blue and 8 spectra in the red photographic region of P Cygni were obtained during 1990. By averaging the spectra in each set a S/N-ratio of about 45 was achieved. Comparing the lists of identifications published by Beals (1950PDAO....9....1B), de Groot (1969BAN....20..225D), Ozemre (1978PIstO.101....1O), Stahl et al. (1993A&AS...99..167S), Markova (1994A&AS..108..561M) and Markova & Zamanov (1995A&AS..114..499M), we conclude that the emission spectrum of P Cygni in our days is probably much richer and intensive than 60 years ago. A number of line parameters of the pure emission lines are measured. An estimate of the electron density and temperature in the region of [NII]-lines formation is obtained. Different velocity laws yielding similar density structures are discussed aiming to account for the results obtained on the basis of the [NII] lines. Possible mechanisms for the formation of the permitted pure emission-line spectrum are proposed.