Masses and radii of white-dwarf stars. III. Results for 110 hydrogen-rich and 28 helium-rich stars.

The basic method for calculating stellar radii is briefly described. It is claimed that systematic errors in the method are approximately 5% for the hydrogen-rich stars, taking into account a discussion of systematic errors in support of that statement. Procedures strictly relevant to the calculations for the H-rich stars are given and procedures for the He-rich stars are discussed. Selection effects are also examined. It is found that the mean radius of a sample of 110 hydrogen-rich stars with parallaxes and good photometry is 0.0127 solar radius. The mean radius of a sample of 28 He-rich stars is 0.0111 solar radius, which, considering the uncertainties, is not significantly different from that of the DA stars.