SPECTROSCOPIC OBSERVATIONS OF PU VULPECULAE IN THE 3210-10950-ANGSTROM RANGE DURING THE NEBULAR PHASE

Spectroscopic observations of PU Vulpeculae have been carried out at t he Observatoire de Kaute-Provence from 1989 June to 1992 September dur ing a decline of brightness from 10.1 to 11.2 in visual magnitude. A s pectral type M6III may be proposed for the cool component from TiO ban d intensities, while the hot surrounding gas is responsible for about 280 emission lines (many of which belong to Fe+ and Fe++ ions), many o f which undergo variations in intensity. Analysis of the [O III] lines reveals a kinetic temperature of about 12 000 K and a lower limit for the electron density of 6.7 x 10(7) cm(-3) in 1991 October, decreasin g by a factor of similar to 2-3 by 1992 September. Helium may be sligh tly overabundant (by a factor of similar to 2) with respect to the sol ar value.