Ejnar Hertzsprung | |
|---|---|
 Hertzsprung in 1961 | |
| Born | (1873-10-08)8 October 1873 Copenhagen, Denmark |
| Died | 21 October 1967(1967-10-21) (aged 94) Roskilde, Denmark |
| Alma mater | Copenhagen Polytechnic (DTU) |
| Known for | Hertzsprung gap Hertzsprung–Russell diagram |
| Spouse | Henriette Mariette Augustine Albertine Kapteijn (1881-1956) |
| Parents |
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| Awards | Bruce Medal(1937) Gold Medal of RAS(1929) |
| Scientific career | |
| Fields | Chemistry,Astronomy |
| Institutions | Leiden Observatory |
Ejnar Hertzsprung (Danish:[ˈɑjnɐˈhɛɐ̯tsˌpʁɔŋ]; 8 October 1873 – 21 October 1967) was aDanish chemist and astronomer. He is best remembered for his role in developing theHertzsprung-Russell diagram of stars.
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Hertzsprung was born inFrederiksberg, Denmark, the son of Severin and Henriette. He studied chemical engineering atCopenhagen Polytechnic Institute, graduating in 1898. After spending two years working as a chemist in St. Petersburg, in 1901 he studiedphotochemistry atLeipzig University for a year.[1] His father was an amateur astronomer, which led to Ejnar's interest in the subject. He began making astronomical observations in Frederiksberg in 1902, and within a few years had noticed that stars with similarspectral type could have widely differentabsolute magnitudes. In 1909, he took a position at theGöttingen Observatory under directorKarl Schwarzschild.[2]
In 1911 Hertzsprung developed theHertzsprung–Russell diagram, independently developed in 1913 byHenry Norris Russell.
In 1913 Hertzsprung determined the distances to severalCepheid variable stars byparallax,[3] and was thus able to calibrate the relationship, discovered byHenrietta Leavitt, between Cepheid period andluminosity. In this determination he made a mistake, possibly a slip of the pen, putting the stars 10 times too close. He used this relationship to estimate the distance to theSmall Magellanic Cloud. From 1919 to 1946, Hertzsprung worked atLeiden Observatory in the Netherlands, from 1937 as director. Among his graduate students at Leiden wasGerard Kuiper.
Perhaps his greatest contribution to astronomy was the development of a classification system for stars to divide them by spectral type, stage in their development, and luminosity. He used the earlier classification system developed byAntonia Maury in his work.[4] The so-called "Hertzsprung–Russell Diagram" has been used ever since as a classification system to explain stellar types andstellar evolution. He also discovered twoasteroids, one of which is1627 Ivar, anAmor asteroid.[5]
His wife Henrietta (1881–1956) was a daughter of the Dutch astronomerJacobus Kapteyn. Hertzsprung died inRoskilde in 1967. The asteroid1693 Hertzsprung was named in his honour.[6]
Media related toEjnar Hertzsprung at Wikimedia Commons
