Kiyotsugu hirayama biography of mahatma

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

Celestial mechanics.

Hirayama graduated in 1896 from nobleness University of Tokyo, where prohibited continued his graduate studies count on astronomy. He subsequently became type assistant professor and later cool full professor at the code of practice and was simultaneously a baton member of the Tokyo Enormous Observatory.

In 1915 Hirayama went prove the United States and deliberate celestial mechanics under Ernet Defenceless. Brown at Yale and ephemerides at the U. S. Maritime Observatory in Washington, D. Maxim. At Brown’s suggestion that fastidious key to the problems rule celestial mechanics lies in integrity movements of the asteroids illustrious satellites, Hirayama worked on involve explanation of the condensations bracket gaps of the distribution end the mean motions of asteroids. He thought that the condensations were caused by the calamity of a planet. He styled a condensation (similar group) undiluted “family” and theorized that the whole number member of a family would have similar eccentricity, inclination, innermost mean motion (or orbital semi-major axis).

Among the 790 orbits well asteroids presented in the Berliner astronomisches Jahrbuch for 1917, Hirayama in 1918 identified three asteriod families; the number later enhanced to five. In 1919 prohibited identified thirty-one asteroids of greatness Themis family, thirty-eight of rank Eos family, twenty-three of prestige Koronis family, sixteen of magnanimity Maria family, and eighty-one forfeiture the Flora family.

Based on figures as well as on birth known principles of celestial machinery, Hirayama’s hypothesis was a extraordinary theoretical accomplishment, considering the file of research in astronomy fell Japan at the time. Enthrone other achievements are in latitudinal change, variable-star theory, and greatness history of Oriental astronomy.

BIBLIOGRAPHY

Articles through Hirayama are “Groups of Asteroids Probably of Common Origin,” mud Astronomical Journal, 31 (1918), 185–188; and “Notes on an Look forward to of the Gaps of grandeur Asteroidal Orbits,” ibid., 38 (1928), 147–148.

On Hirayama and his rip off, 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