Cepheid distances from blue main-sequence companions.

Abstract

The author determines the absolute visual magnitudes of main-sequence Cepheid companions from their effective temperatures. These are obtained by comparing the measured relative energy distributions with model atmosphere energy distributions. Assuming an average galactic extinction law, it is found that the distance moduli for the Cepheids should be smaller by Δ(m_v-M_v) = -0.5 as compared to the Sandage-Tammann relation.