Nova V351 Puppis 1991: A multiwavelength study of the nebular phase

We combine ground-based optical and IUE spectrophotometry to study the physical conditions in the shell of Nova V351 Puppis 1991. The structure and the evolution of the shell during the early nebular (i.e. optically thin) phase are discussed in this paper. The reddening, derived from recombination lines, is E(B - V) = 0.72 +/- 0.10. The optical/UV light curves imply a distance of 3.0 +/- 0.5 kpc. These values are found to be consistent with a study of the reddening in the stellar field near the nova. Abundances from the emission-line spectra yield enhancements within the predictions of thermonuclear runaway models for classical novae, Relative to solar by number, they are: He/H = 1.7, C/H = 3.5, N/H = 130, O/H = 38, Ne/H = 120, Al/Si = 28. The shell shows a low ejected mass (M(ej) similar to 10(-7) M(.)), implying a high-mass white dwarf. The optical spectra reveal a strong red excess, which we tentatively attribute to the red companion. The strength of this continuum suggests that the companion is either a giant or an irradiated main-sequence star.