The radii of Galactic Cepheids as determined from a version of the Baade-Wesselink technique are shown to depend upon the colour index used to define the temperature scale. The (V-I) radii are systematically larger than the commonly used (B-V) radii and are probably better estimators of the true radii. There still remains a problem, however, in reconciling the period-radius relation with the period-luminosity-colour relation.
IAU Colloq. 82: Cepheids: Theory and Observation
- Pub Date:
- June 1985