Ultraviolet observations of beta Canis Majoris stars with the TD-1 A satellite.

Ultraviolet observations of 21 Beta CMa stars obtained with the S59 and the S2/68 experiments on board the TD-1A satellite have been combined to estimate the ranges of the light variations in the ultraviolet. The Beta CMa stars seem to have the same colors and spectral features as 'normal' stars in the ultraviolet (at the S2/68 resolution), except for Beta Cep, Xi-1 CMa, and Sigma Sco. The variations of effective temperature and radius have been computed from the ultraviolet and visual light ranges on the basis of radial pulsations, assuming that the light curves are in phase at all wavelengths used. The values of the radius variations and of the ratios characteristic of the pulsations derived from these quantities are discussed.