A survey of Cepheid sizes

The radius is one of the fundamental physical parameters governing a Cepheid's pulsation. If the radius of a Cepheid can be established independently of its luminosity and temperature, that radius, combined with a temperature scale, can yield the Cepheid's luminosity. The Baade-Wesselink (BW) method provides an approach for determining a Cepheid's radius independently of any temperature or luminosity scale. In connection with the present investigation, data regarding individual BW radius determinations are provided in a table. The best BW radii are selected and a period-radius (P-R) relation is determined. The obtained relation is compared to theoretical P-R relations. The BW and theoretical relations are compared to one obtained from the luminosities and temperatures of Cepheids in open clusters and associations.