WALTER BAADE

Walter Baade 1893-1960

Walter Baade was a German-born American astronomer who classified the stars into two distinct types of people. The father of Walter Baade, Konrad Baade, a professor of school. Parents are Protestant religion and theology are a career for their son.
Walter received an excellent education that allows him to speak and read Greek and Hebrew. From primary school in Herford (from 1903 to 1912), he was attracted by astronomy. Following a brief stint at the University of Münster, he attended the University of Göttingen. During the First World War, he studied at the observatory with Leopold Ambrona Felix Klein and assists for three years.
Exempted from military service because of a congenital hip dislocation, but in 1917, he worked in a test installation of prototype aircraft.
In 1919 he obtained his doctorate. He gets a job as an assistant at the observatory of the University of Hamburg, Bergedorf, where he worked for eleven years.
Its task is to observe comets and in 1923 he discovered a comet.
In 1927 he published a study on the morphology of the tails of comets.
In 1925, he discovered the asteroid Hidalgo.
In 1920 born his interest in globular clusters and variable stars.
In 1926, he tried to prove that the variability of these stars comes from the fact that their radiating surfaces grow.
That same year, due to the work Bergedorf, he received a Rockefeller fellowship to visit the major observatories in California. In 1931, Baade accepted a position at the Mount Wilson Observatory.

In 1933 he invited his friend to join Rudolf Minkowski and both work in spectroscopy.
He also works with Hubble on distant galaxies and with Fritz Zwicky of supernovae and novae. During World War II, it is considered a potential enemy.
He can not leave Pasadena because it has no map of U.S. citizenship. In fact, before the war, he lost his papers and forget to do it again.
It did him service as most astronomers were requested for the war effort. However, it has free access, large telescopes and a curfew in Los Angeles offered him a light sky cleared.
It will benefit from this windfall to make a thorough study of the great Andromeda galaxy and its two satellite galaxies.
It is a productive period of research for Baade. He introduced the concept of "stellar populations", when he notes that the bright stars of the core are red and not blue like the arms.
In 1952, he discovered two types of Cepheids, these stars are used in the calibration of the distance of galaxies, astronomers will bring it to double all extragalactic distances. Baade Telescope using the Hale 5-meter Palomar Mountain and is interested in astronomy which allows it to locate more intense radio sources in the optical domain.
In 1958, he stopped his career and he became a lecturer at Harvard, spent six months in Australia, uses a low of 1.78 m telescope of Mount Stromlo and then returned to Göttingen.
In 1960, Walter Baade died of respiratory failure.

Image: Walter Baade was one of the giants of astronomy in the first half of the 20th century, he did not write, but what he published was of paramount importance.