Early nebular stage of Nova Cygni, 1975

The emission line profiles of the spectrum of the envelope of Nova V 15O0 Cyg, 1975 are studied. The spectral region covers lambda lambda 3700-4500, H#betta# and lambda lambda 6500-8800. The velocity structure of the profiles and the time variation of both the velocities and intensities of the emission peaks of Hα are interpreted as due to an expanding system of rings at different latitudes with respect to a common polar axis. The envelope was optically thick to Balmer line radiation and was thinning out rapidly during the period of observation. (author)