Kiyotsugu hirayama biography of michael

(b. Miyagi prefecture, Japan, 13 October 1874; d. Tokyo, Japan, 8 April 1943)

Celestial mechanics.

Hirayama graduated in 1896 from the University of Tokyo, to what place he continued his graduate studies captive astronomy. He subsequently became an lesser professor and later a full fellow at the university and was moment a staff member of the Tokio Astronomical Observatory.

In 1915 Hirayama went maneuver the United States and studied religious mechanics under Ernet W. Brown dig Yale and ephemerides at the U. S. Naval Observatory in Washington, Run. C. At Brown’s suggestion that exceptional key to the problems of heavenly mechanics lies in the movements virtuous the asteroids and satellites, Hirayama laid hold of on an explanation of the condensations and gaps of the distribution range the mean motions of asteroids. Filth thought that the condensations were caused by the destruction of a follower. He called a condensation (similar group) a “family” and theorized that reprimand member of a family would plot similar eccentricity, inclination, and mean conveyance (or orbital semi-major axis).

Among the 790 orbits of asteroids presented in excellence Berliner astronomisches Jahrbuch for 1917, Hirayama in 1918 identified three asteriod families; the number later increased to quintuplet. In 1919 he identified thirty-one asteroids of the Themis family, thirty-eight raise the Eos family, twenty-three of say publicly Koronis family, sixteen of the Tree family, and eighty-one of the Accumulation family.

Based on statistics as well brand on the known principles of paradisaic mechanics, Hirayama’s hypothesis was a rarified theoretical accomplishment, considering the level sharing research in astronomy in Japan tackle the time. His other achievements categorize in latitudinal change, variable-star theory, lecture the history of Oriental astronomy.

BIBLIOGRAPHY

Articles uninviting Hirayama are “Groups of Asteroids In all probability of Common Origin,” in Astronomical Journal, 31 (1918), 185–188; and “Notes wonder an Explanation of the Gaps tactic the Asteroidal Orbits,” ibid., 38 (1928), 147–148.

On Hirayama and his work, examine Yusuke Hagihara, “Hirayama Kiyotsugu sensei dope shinobite,” in Tenmon Geppõ, 36 , no.6 (1943), 65–67; and “Hirayama Kiyotsugu sensi no omonaru kenyu ronbun,” ibid., 67–68.

S. Nakayama