Kiyotugu HIRAYAMA'S Study of Variable Stars : on the Comparing K. HIRAYAMA'S Study with S.SHINJYO's Study

Abstract

The purpose of this paper is the assessment of K. HIRAYAMA's study of Cepheid variable stars in Japanese and in the international trend of studying the variable stars. K. HIRAYAMA published four papers about variable stars in 1931 and in 1932, and he formed the contact theory which was one of the non-pulsation theories of Cepheid variable stars. S. SHINJYO, who was the Japanese researcher of Cepheid variable stars before K. HIRAYAMA, published five papers about variable stars from 1922 to 1926, and he formed the eccentric nucleus theory which was one of the non-pulsation theories of Cepheid variable stars. It was interesting to note that those researchers formed the non-pulsation theory after H. Shapley's study of the pulsation theory of Cepheid variable stars in 1914 and A.S. Eddington's study of the pulsation theory of Cepheid variable stars in 1919. S.SHINJYO and K.HIRAYAMA formed these non-pulsation theories in order to explain not only mechanism of the variable stars but also the energy source of stars and the stellar evolution. We concluded that their study of these non-pulsation theories was one of the evidence that the pulsation theory was established during 1930's at which the energy source of stars and the stellar evolution were established.