Ejnar hertzsprung biography of abraham

Born Oct. 8, , in Frederiksberg, Denmark; died Oct. 21, , in Tølløse, Denmark.

Hertzsprung was born in Frederiksberg , Denmark, the son of Severin and Henriette. He studied chemical engineering at Copenhagen Polytechnic Institute , graduating in After spending two years working as a chemist in St. Petersburg, in he studied photochemistry at Leipzig University for a year. He began making astronomical observations in Frederiksberg in , and within a few years had noticed that stars with similar spectral type could have widely different absolute magnitudes.

In Hertzsprung developed the Hertzsprung—Russell diagram , independently developed in by Henry Norris Russell. In Hertzsprung determined the distances to several Cepheid variable stars by parallax , [ 3 ] and was thus able to calibrate the relationship, discovered by Henrietta Leavitt , between Cepheid period and luminosity.

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 the Small Magellanic Cloud. From to , Hertzsprung worked at Leiden Observatory in the Netherlands, from as director. Among his graduate students at Leiden was Gerard 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 by Antonia Maury in his work. He also discovered two asteroids , one of which is Ivar , an Amor asteroid. His wife Henrietta — was a daughter of the Dutch astronomer Jacobus Kapteyn. Hertzsprung died in Roskilde in