Effective Temperatures of the Central Stars of Planetary Nebulae

The effective temperatures of the central stars of thirty-five planetary nebulae are determined on the assumption that the central stars are non-gray and that there is complete absorption in the He+ Lyman continuum in each case The model atmospheres of Böhm and Deinzer that correspond to the Harman and Seaton sequences of stars with masses between 0.5 and 1 solar mass are assumed to be representative of the atmospheres of the centra] stars of planetary nebulae. Upper and lower limits are set to the characteristic optical thickness at the Lyman limit in the HO continuum for each object under consideration