Estimation of errors in the distances to intrinsically reddened stars

We show that adding the intrinsic color excess DeltaE(B-V), of a star to th e interstellar EB-V, can significantly change the estimate of its distance r. When DeltaE(B-V) changes from 0.(m)0 to 0.(m)5, the relative error delta in the estimated distance rapidly increases to 99.5%. For DeltaE(B-V) > 0. (m)5, r cannot be determined front the distance modulus. The error delta de pends neither on absolute Magnitude nor oil apparent Magnitude m(V), nor on interstellar extinction but depends only oil the star's intrinsic reddenin g DeltaE(B-V). We provide quantitative estimates of the intrinsic reddening - in stars. The mean values of <(<Delta>EB-V)over bar> for B0 Stars, in Ope n Clusters and associations are 0.(m)2 and 0.(m)35, respectively <(<Delta>E B-V)over bar> for Be stars is 0.(m)1-0.(m)2; the effect of cooler companion s oil the color indices of OB stars can vary. The individual values of Delt aE(B-V) for separate OB stars exceed 0.(m)5 and reach 0.(m)6-0.(m)7, We sho w that the intrinsic reddening Of cluster stars produced by circumstellar g as-dust envelopes call be separated from the interstellar reddening even fo r the same extinction law. (C) 2001 MAIK "Nauka/Interperiodica".