著者

吉田 省子

出版者

日本科学史学会

雑誌

科学史研究 (ISSN:21887535)

巻号頁・発行日

vol.41, no.224, pp.203-213, 2002 (Released:2021-08-13)

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Kiyotsugu Hirayama (1874-1943), who is renowned for his finding of families of asteroids in 1918, had two astronomical interests in addition to the family after his return home from U.S. (1915-1917): the explanation of gaps in the distribution of the mean motion of the asteroids, and the theory of stellar evolution including the origin of binary system and the origin of stellar energy and the mechanism of the periodic variable stars. Although it seemed as if his researches of stellar evolution originated in another interest different from asteroid-researches, certainly it's half-true, all these were interrelated, too. No one states this view. He approached these problems through celestial mechanics. Given resisting particles in the solar system, he considered theoretical effect of resistance on the motion of the asteroids in the librating region. And he speculated the capture theory of the stars that the cloud (mass of resisting particles) in the interstellar space can capture several stars passing through it. He said that his capture theory was naturally connected with the stellar evolution. In short, resisting particles (medium) was his key idea. His capture theory was an extension of the asteroid-researches under the resisting-medium hypothesis. But the theory not only was an extension of asteroid-researches, but also was caused by general interest shared with astronomers at the time. Finally, physical ground of his statement in 1933 that the outbreak of the asteroid families might have occurred after the medium had dissipated, was on his theory of solar system formation based on his capture theory.