On the possibility of systematizing classical novae by light curve type. II. Observational characteristics of novae and groups

Abstract

The separation of novae into groups, proposed in Part 1 of this paper, is discussed: it is based on the criterion of the shape of the light curve, plotted on “outburst amplitude-logarithm of shell radius ” scales. The observational characteristics of novae belonging to certain groups are considered. Novae of the GQ Mus group may be characterized by x ray emission. The proposed separation of novae into groups may be related to the structure of the shell ejected in the outburst. Novae with smooth light curves have ellipsoidal shells without pronounced nonuniformities. Novae with temporary fading or with brightness fluctuations in the transitional stage of the outburst have ellipsoidal shells with a nonuniform distribution of matter (equatorial and tropical belts in novae of the DQ Her group, an equatorial belt for the RR Pic group, and a patchy structure for the CP Pup group). Relationships among certain parameters of novae are considered: absolute stellar magnitude, outburst amplitude, shell expansion velocity, etc. From the “depth of temporary fading in the transitional stage of the outburst-shell expansion velocity” dependence it can be concluded that the kinetic energy of the shell may be a constant for novae of the DQ Her group.