Ultraviolet spectral variations of symbiotic nova PU Vul during and after second eclipse

Abstract

I have analyzed spectral data of the symbiotic nova PU Vul observed with the International Ultraviolet Explorer (IUE) during the period 1993–1996. The study concentrated on the two sources of nebular emitting regions, the first is a nebula around the white dwarf partially eclipsed by a cool giant star and the second is a very extended nebular region not affected by the eclipse of the giant star. I concentrated on the N IV] 1486 Å and C IV 1550 Å emission lines produced in the first region and N III] 1750 Å and C III] 1909 Å emission lines produced in the second region very far from the giant star. The outflow velocity of the two emitting regions was calculated to be 1200–1500 km s^‑1 and 1300–1900 km s^‑1 (FWHM). I estimated the reddening from the 2200 Å absorption feature, E(B‑V)=0.46±0.02. The average wind mass loss rate for the first region is estimated to be ∼1.5×10‑5M⊙, the average temperature of the first emitting region is estimated to be ∼1×105K and and the average ultraviolet luminosity of the first region is estimated to be 2×1035ergs‑1. The results show that the line fluxes of the first region are affected by the second eclipse, while the line fluxes of the second region are not affected by this eclipse. The variable ultraviolet emission lines for the first region during and after second eclipse are attributed to the variable wind mass loss rate from the hot white dwarf, while the gradual decline of emission lines for the second region is attributed to the cooling of the nebulae after long period of time since the outburst in 1977.