- Pieter Oosterhoff
Pieter Theodorus Oosterhoff (1904-1978) was a Dutch
astronomer .He was the co-administrator, along with
Jan Oort , of theLeiden Observatory in the Netherlands.He published papers were primarily in regard to
variable star s andphotometry . He is most noted for observing in 1939 that there appear to be two populations ofglobular clusters based on the periodicities of theirRR Lyrae variable stars. [cite journal | author=Oosterhoff, P. T. | title=Some remarks on the variable stars in globular clusters | journal=The Observatory | year=1939 | volume=62 | pages=104–109 | url=http://adsabs.harvard.edu/abs/1939Obs....62..104O ] These two populations would come to be known as "Oosterhoff groups" after him.Between 1951 and 1952 he served as assistant general secretary of the
International Astronomical Union , and served as general secretary from 1952 until 1958. In 1954 he was one of twelve European astronomers who drafted a statement that would lead to the formation of the ESO.The
asteroid 1738 Oosterhoff is named after him.References
External links
*cite web | date = 2000-11-01 | url = http://eaa.iop.org/index.cfm?action=summary&doc=eaa%2F3902%40eaa-xml | title = Oosterhoff, P Th (1904–78) | publisher = Institute of Physics Publishing | language = English | accessdate = 2006-06-08
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