Determination des rayons de cepheides. I. Vitesses radiales et dimensions de XY Cas.
Abstract
We have observed the classical cepheid XY Cas, of B magnitude 11.1, with the Coravel radial velocity spectrometer. From 47 high accuracy velocities, and from UBV measurements of Mitchell et al. and of Szabados, we have determined the radius of this star by Wesselink's method.
This determination was done by resolving a system of equations of the type
V = α(BV)  5log∊. log_{∊} (l + D_{α}/R_{α}) + K
We calculated the magnitudes, V, and the colour indices, BV, for 280 epochs within one period, by a limited Fourier development from the observations. The values D_{α} = ∆R/p of the displacement, for the same a epochs, were calculated by a Fourier development deduced by integration from that for the radial velocity. We obtain a radius of 41.6 ± 0.8 R_{sun}, which is perfectly compatible with the most recent period radius relations.
 Publication:

Astronomy and Astrophysics Supplement Series
 Pub Date:
 May 1981
 Bibcode:
 1981A&AS...44..319I
 Keywords:

 Cepheid Variables;
 Radial Velocity;
 Radii;
 Stellar Motions;
 Stellar Spectrophotometry;
 Accuracy;
 Electrophotometers;
 Stellar Magnitude;
 Astronomy