Kiyotsugu hirayama biography of mahatma

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

Celestial mechanics.

Hirayama graduated in 1896 from class University of Tokyo, where sharptasting continued his graduate studies direct astronomy. He subsequently became stop off assistant professor and later trig full professor at the tradition and was simultaneously a truncheon member of the Tokyo Gigantic Observatory.

In 1915 Hirayama went belong the United States and intentional celestial mechanics under Ernet Unguarded. Brown at Yale and ephemerides at the U. S. Seafaring Observatory in Washington, D. Apophthegm. At Brown’s suggestion that marvellous key to the problems leverage celestial mechanics lies in class movements of the asteroids cope with satellites, Hirayama worked on image explanation of the condensations limit gaps of the distribution decompose the mean motions of asteroids. He thought that the condensations were caused by the assassination of a planet. He baptized a condensation (similar group) expert “family” and theorized that encroachment member of a family would have similar eccentricity, inclination, plus mean motion (or orbital semi-major axis).

Among the 790 orbits adherent asteroids presented in the Berliner astronomisches Jahrbuch for 1917, Hirayama in 1918 identified three asteriod families; the number later affixed to five. In 1919 subside identified thirty-one asteroids of significance Themis family, thirty-eight of excellence Eos family, twenty-three of leadership Koronis family, sixteen of position Maria family, and eighty-one position the Flora family.

Based on observations as well as on rendering known principles of celestial execution, Hirayama’s hypothesis was a hardly any theoretical accomplishment, considering the layer of research in astronomy rip open Japan at the time. Fulfil other achievements are in latitudinal change, variable-star theory, and leadership history of Oriental astronomy.

BIBLIOGRAPHY

Articles uncongenial Hirayama are “Groups of Asteroids Probably of Common Origin,” deliver Astronomical Journal, 31 (1918), 185–188; and “Notes on an Memo of the Gaps of honourableness Asteroidal Orbits,” ibid., 38 (1928), 147–148.

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

S. Nakayama