The physical conditions and velocity distribution in the envelope of RR Telescopii

Spectra of the slow nova RR Telescopii, taken at the Radcliffe Observatory during its nebular stage, were spectrophotometrically examined. Half- intensity widths were measured for lines with little blending. If these widths are interpeted as expansion velocities, the velocities are greater for lines produced by ions of greater ionization potential, but decreased with time for each stage of ionization. Such effects can be understood if deceleration is assumed to occur in an envelope ionized by radiation from a central star of changing surface temperature; in this model there will be associated changes in the size of ionization regions but the highest ionization will occur close to the star. Mean electron temperatures were determined for the envelope, but they are probably higher near the central star. The ratio of He II to H recombinations was determined for one date (1965) and can be interpreted as either due to a temperature of order 2000000 (by Ambartsumian's method) or to an abundance ratio of order He Il/H = .