Physical Parameters of Prenovae and Outburst Amplitudes

Abstract

The best observed novae of C. Payne-Gaposchkin’s list and the brightest novae found since 1960 yield 37 data points in a diagram showing absolute magnitudes of novae at minimum light versus amplitude of the outburst. Three dwarf novae are found well separated from the novae, five recurrent novae mix with the high luminosity end of the nova sequence. Due to the small scatter in absolute magnitudes at maximum a noticeable dependence of outburst amplitude on M_min which ranges from 9^m to brighter than O^m, is found. For eleven novae blue spectra at minimum indicate high temperatures. O-type temperatures and white dwarf densities are, however, mutually exclusive over a wide range of M_min. Only two novae, CP Pup and V1500 Cyg, have, under the assumption of O-type temperatures, densities within the white dwarf range and even they are found near the low-density limit. This leaves three explanations for minimum light:

• 1) All prenovae are normal white dwarfs, additional light comes from a sufficiently bright blue disk.

• 2) All prenovae are white dwarfs with a much wider range of temperatures than hitherto assumed - up to more than a million degrees.

• 3) All prenovae are O-type stars with a wide range of densities. These assumptions lead, respectively, to a: 1) disk-amplitude relation; 2) temperature-amplitude relation; 3) density-amplitude relation; stating that fainter disks, lower temperatures or higher densities agree with more spectacular nova outbursts.