A new pulsational radius for Delta Cephei

Abstract

The Baade-Wesselink method has been reapplied to existing photometric and radial-velocity measures for the classical Cepheid [delta] Cephei, but a different approach to the analysis was adopted in which spectrophotometric narrowband KHG observations were used to isolate phase pairs of identical atmospheric temperature. Corrections for variable spectral-line blocking and changing effective gravity in the observed V magnitudes and B — V colors were analyzed semiempirically, and a solution obtained by minimizing the relative error in the result. The mean radius found for [delta] Cephei is 42.7R[subscript circled dot] [plus or minus] 1.0R[subscript circled dot], which is quite close to other recently derived radius estimates for this Cepheid, including theoretical values obtained from the secondary bump on its light curve.