Absolute emission-line intensities for V1016 Cygni.

Photometric and spectrophotometric observations have been made of 1 016 Cygni to determine the absolute intensities of the brighter emission lines. The Balmer decrement is much less steep than it was when measured in 1966 by O'Dell. Since the total brightness of the nebula has not increased since 1966, this cannot be interpreted as a decrease in reddening. We postulate an additional source of Ha emission which has since disappeared. The forbidden-line intensity ratios indicate a 1973 density of log Ne = 6.86 i 0.04, and temperature of Te = 11,900 i 500 K. The change in the intensity ratio [0 ii'] A43631[O ii'] A5007 and [0 iii] A4959/Hfl indicates that the density has not decreased by more than a factor of 1.6 between 1966 and 1973. A stratification model is presented for the case of a sphere of uniform density and temperature, and the relative intensities of He ii A4686/H imply a blackbody effective temperature of T* = 164,000 i 3600 K for the central star. If the Balmer line optical depth arises from hydrogen in the 2s state, we infer a radius of 1.0 >c 1016 cm and a mass of 0.027 M0.. Photometric observations relative to NGC 7027 indicate an Hfl flux of 3.69 + 0.20 x 10-li ergs s . Subject headings: planetary nebulae - stars, individual - stellar evolution