Ejnar Hertzsprung
Ejnar Hertzsprung ( born October 8, 1873 in Frederiksberg, † October 21, 1967 in Tølløse, in today's Vestsjællands Office) was a Danish astronomer.
Life and work
After 1898, the completed study chemistry Hertzsprung worked for several years in Saint Petersburg. In 1902 he went to Leipzig to study photochemistry of Wilhelm Ostwald. After his return in 1902 he devoted himself first astronomical studies, which he pursued at the University and the Urania Observatory in Copenhagen. 1909 Hertzsprung learned Karl Schwarzschild know who gave him a professorship at the University of Göttingen and whom he followed to Potsdam 1909.
1919 Hertzsprung went to the University of Leiden Observatory (Netherlands), which he directed from 1935 to 1944.
Hertzsprung has made important contributions to the development of modern astrophysics with his research. In 1905 he defined with the absolute brightness is a measure of the luminosity of a star. He also discovered that, for stars of the same surface temperature can occur giant stars and dwarf stars, which he created a classification feature. 1909 Hertzsprung worked on surface temperature -luminosity relations. To clarify the question of whether there are cold and hot luminous stars, he developed a temperature -luminosity diagram. 1911 Hertzsprung discovered small fluctuations in brightness of the polar star, which he could assign him the Delta Cepheids (stars with periodic change of brightness ).
In 1913 he succeeded the first distance determination to Cepheids in the Small Magellanic Cloud. Together with the period-luminosity relation of Henrietta Swan Leavitt could be determined to more distant Cepheids in other galaxies as well as the first time distances. However, the calculated distance to the Small Magellanic Cloud of about 3,000 light- years was wrong. We know today that the Small Magellanic Cloud is about 70 times further away. Nevertheless, it is at the former distance determination is an important astrophysical pioneering.
Also in 1913, learned to be temperature -luminosity diagram by Henry Norris Russell, a review or appropriate publication ( Hertzsprung -Russell diagram, HRD ). 1915 Hertzsprung dedicated the double stars, whose observation he developed a photographic precision technology. This Hertzsprung also discovered the asteroid ( 1702) Kalahari. He also found a relationship between mass and luminosity, which he formulated in 1919 in a general form for the main sequence stars in the HRD.
In 1929 he was awarded the Gold Medal of the Royal Astronomical Society.
In his honor, received a 1935 -discovered asteroid the name ( 1693) Hertzsprung.