The nebular stage of nova PW Vulpeculae.

Abstract

UV and optical nebular spectra of Nova PW Vul were used to derive plasma parameters of the ejected shell. From the visual lightcurve decay times of t2 = 83 days and t3 = 147 days are estimated, which indicate that PW Vul is a slow nova. A color excess of E(B - V) = 0.55 and a distance of about 1.3 kpc were derived. Emission line fluxes were dereddened and used to determine electron temperatures T(e) of 15,000 K and 10,300 K characteristic for the N(4+) and C(2+) formation regions, respectively. An electron density N(e) of about 10 million/cu cm was determined for the O(2+) and N(+) emission regions, and can be considered as typical value for large fractions of the envelope. He is about solar, C and O are 10 to 30 times overabundant, and N about 200 times relative to cosmic abundances in agreement with predictions from the thermonuclear runaway theory.