Kiyotsugu Hirayama

Hirayama Kiyotsugu ( Japanese 平山清次 ; born October 13, 1874 in Sendai , † April 8, 1943 in Tokyo ) was a Japanese astronomer .

biography

Hirayama was the only son of a shipbuilder. He grew up in Sendai, where he studied Classical Chinese , Foreign Languages and General Studies. From 1894 he attended the Imperial University of Tokyo . After graduating with a major in astronomy in 1897 , he worked at the Tokyo Astronomical Observatory , which was affiliated with the university. Its main task was the acquisition of geodetic data from the determination of longitudes and latitudes through astronomical observations. He made several publications on the subject in the Astronomical News . In 1906 he was sent to the occupied island of Sakhalin to precisely determine the 50th parallel as a border after the end of the Russo-Japanese War (1904–1905). After his return he was promoted to scientific assistant in 1906. His duties also included calculating the ephemeris of planets and the moon .

In 1911 he became a doctor of natural sciences. In 1916 he went to the United States to attend the University of Yale celestial mechanics to study. There he worked on part of Ernest William Brown's study on the motion of the moon. At Yale, he became interested in asteroids .

After returning to Tokyo in 1918, he published his theory on asteroid families. In 1919 he was promoted to professor, which he also taught. He also dealt with the history of astronomy and published on the subjects of solar eclipses , Halley's comet , leonids and comets .

He retired in 1935 and died on April 8, 1943.

Scientific work

He became known for his discovery that several asteroids can be assigned to asteroid families due to similar orbits , orbital inclination and eccentricity . A family emerged from the collapse of a larger planetoid through collisions. These families are also called the Hirayama families . The largest object in a group is its namesake. When first published in 1918, he described the groups of the Themis , Eos , and Koronis families. Through his analysis of the orbital data of over 1,000 asteroids, the Maria , Phocaea , Flora and Pallas families were added in the 1920s .

Namesake

The asteroid (1999) Hirayama bears his name.
The 132 km large lunar crater Hirayama 6 ° 6 ′ 0 ″ S , 93 ° 30 ′ 0 ″ E was named after him and the astronomer Shin Hirayama .Moon -6.1 93.5

Asteroid families are also named Hirayama family in his honor .

Trivia

Kiyotsugu Hirayama is sometimes confused with the astronomer Shin Hirayama (1868–1945), who was also a professor at Tokyo University until 1928. Shin Hirayama was the first to observe the asteroids (498) Tokyo and (727) Nipponia . But since he could not determine its orbit, their discovery was ascribed to other astronomers.

Publications (selection)

"On a systematic error of the latitude observed with a zenith telescope" in " Astronomische Nachrichten ", Volume 176 (1907)
"Halley's Comet in Japanese history" in "The Observatory", No. 33, pp. 130-133 (1910)
"On the comets of AD 373 and 374" in "The Observatory", No. 34, pp. 193-199 (1911)
"Groups of Asteroids Probably of Common Origin" in "Astronomical Journal", No. 31, pages 185-188 (1918)
"Further Note on the Families of Asteroids" in "Journal of the Physical Society of Japan", No. 1 (1919)
"New Asteroids Belonging to the Families" in "Journal of the Physical Society of Japan", No. 2 (1920)
"Families of Asteroids" in "Japan Journal of Astronomy and Geophysics", No. 1 (1922)
"Families of the Asteroids, Second Paper" in "Japan Journal of Astronomy and Geophysics", No. 5 (1927)
"Records of Leonids in the Far East" in "The Observatory", No. 52, pages 241-246 (1929)
"Calendrical and Time Systems" in "Tokyo, Kouseisya" (1933)
"Present state of the families of asteroids" in "The Proceeding of the Imperial Academy of Japan", No. 9, pages 482-485 (1933)

Web links

Publications by K. Hirayama in the Astrophysics Data System

Individual evidence

↑ ^a ^b Yoshihide Kozai: Hirayama, Kiyotsugu . In: Thomas Hockey, Virginia Trimble, Thomas R. Williams, Katherine Bracher, Richard Jarrell, Jordan D. Marché, F. Jamil Ragep (Eds.): Biographical Encyclopedia of Astronomers . Springer, New York 2007, ISBN 978-0-387-30400-7 , pp. 513 , doi : 10.1007 / 978-0-387-30400-7_631 (English, Biographical Encyclopedia of Astronomers in the Google book search [accessed July 14, 2017]).
↑ ^a ^b ^c ^d ^e Yoshihide Kozai: Kiyotsugu Hirayama and His Families of Asteroids . Ed .: Yoshihide Kozai, Richard P. Binzel, Tomohiro Hirayama (= Astronomical Society of the Pacific Conference Series . Vol. 63). Astronomical Society of the Pacific , San Francisco 1994 (English, harvard.edu [accessed July 14, 2017]).
↑ Seiko Yoshida, Tsuko Nakamura: Hirayama Kiyotsugu: Discoverer of Asteroid Families . In: Wayne Orchiston, Tsuko Nakamura, Richard Strom (Eds.): Highlighting the History of Astronomy in the Asia-Pacific Region (= Astrophysics and Space Science Proceedings ). Springer, New York 2011, ISBN 978-1-4419-8161-5 , doi : 10.1007 / 978-1-4419-8161-5_10 (English, springer.com [accessed July 14, 2017]).

personal data
SURNAME	Hirayama, Kiyotsugu
ALTERNATIVE NAMES	平山清次 (Japanese)
BRIEF DESCRIPTION	Japanese astronomer
DATE OF BIRTH	October 13, 1874
PLACE OF BIRTH	Sendai
DATE OF DEATH	April 8, 1943
Place of death	Tokyo

[Ency-1] Yoshihide Kozai: Hirayama, Kiyotsugu . In: Thomas Hockey, Virginia Trimble, Thomas R. Williams, Katherine Bracher, Richard Jarrell, Jordan D. Marché, F. Jamil Ragep (Eds.): Biographical Encyclopedia of Astronomers . Springer, New York 2007, ISBN 978-0-387-30400-7 , pp. 513 , doi : 10.1007 / 978-0-387-30400-7_631 (English, Biographical Encyclopedia of Astronomers in the Google book search [accessed July 14, 2017]).

[:0-2] Yoshihide Kozai: Kiyotsugu Hirayama and His Families of Asteroids . Ed .: Yoshihide Kozai, Richard P. Binzel, Tomohiro Hirayama (= Astronomical Society of the Pacific Conference Series . Vol. 63). Astronomical Society of the Pacific , San Francisco 1994 (English, harvard.edu [accessed July 14, 2017]).

[3] Seiko Yoshida, Tsuko Nakamura: Hirayama Kiyotsugu: Discoverer of Asteroid Families . In: Wayne Orchiston, Tsuko Nakamura, Richard Strom (Eds.): Highlighting the History of Astronomy in the Asia-Pacific Region (= Astrophysics and Space Science Proceedings ). Springer, New York 2011, ISBN 978-1-4419-8161-5 , doi : 10.1007 / 978-1-4419-8161-5_10 (English, springer.com [accessed July 14, 2017]).