Circumstellar dust envelope of novae

Studies have led the author to conclude that all Novae are surrounded by a dusty envelope. This envelope which has a radius of 5 x 1014 to 5 x 1015cm, exists before the explosion of the Nova. Visual absorptions have been measured of the circumstellar dusty envelope of Nova Delphini of the order of 1.12, 3.29, and 2.24 magnitudes in 1968, 1969, and 1970, respectively, while that of Nova Serpentis was of the order of 3 magnitudes at the start of its activity. Also the ratio has been found of visual absorption to the colour excess Esub(B-V) for Nova Delphini, which was of the order of 2.35, 2.75, and 3.36 for 1968, 1969, and 1970, respectively. Therefore, it is seen that the effect of the reddening of the circumstellar envelope on the line fluxes is very large; thus the flux of Hsub(β) needs to be multiplied by a factor of order 30, to eliminate the effect of circumstellar reddening. It is also found that the particles of the circumstellar envelope have a radius of 0.1 micron before the explosion and that, in order to interpret the observed phenomena, one must consider the 0.1 micron radius particles as condensation nuclei, for the formation of large particles. The increase of particle radius during the activity of a Nova is due to collisions between dust particles (which exist before the explosion) and gas ejected by the Nova. (Auth.)