On the Atmospheric Structure of ζ Aurigae.

Photoelectric observations of ~ Aurigae made at the Steward Observatory during the ingress of its recent eclipse in December, 1939, together with those of Kron and of Guthnick and Schneller are inter- preted according to two hypotheses; first, a geometrical eclipse the partial phase of which lasts 1.3 days and, second, the gradual extinction of the B star by the atmosphere of the K star. In order to obtain a temperature for the B star consistent with its spectral class a central eclipse is not possible if the partial phase is due to a geometrical eclipse. The extinction solution gives a good representation of the observations, especially when the points of Kron and of Guthiiick and Schneller are corrected to the effective wave length of the Tucson observa- tions. The consequences of the acceptance of extinction as the mechanism of obscuration are discussed. Color observations both in and out of eclipse are recorded