A Method for Determining the Intrinsic Colors of Cepheids from Their Periods and Light Amplitudes

It is shown that the equations (B - V)%ax = 0.297 + 0.307 log P - O.t94 AV, (B- V) = 0.238 + 0.373 log P + 0.373 AV, allow the determination of the color excesses of classical Cepheids to an average accuracy of 0.03 mag. A heuristic argument is given that indicates the basis of these expressions.