Allan Sandage
Allan Sandage was born on June 18, 1926. He was an American
astronomer, best known for his work with Edwin Hubble.
In
1948, Sandage graduated from the University of Illinois, and went on to receive
a PhD from the California Institute of Technology in 1953, with astronomer
Walter Baade as his mentor. Sandage worked as an assistant to cosmologist Edwin
Hubble, and continued his research after Hubble’s death in 1953. In 1952,
Sandage proved both prestigious astronomers to be mistaken in a study of
Cepheid variable stars, showing that the brightest stars in galaxies were of
approximately equal inherent intensity, and that Baade was mistaken in the case
of H II regions which he found not to be stars and inherently brighter than the
brightest stars in distant galaxies. Sandage then calculated the age of the
universe to be approximately 5 and a half billion years, which was an increase
of a factor of 1.5 from what was previously calculated.
Allan
Sandage then began working at the Palomar Observatory, and in 1958 published
the first good estimate for the Hubble constant. He edited Hubble’s previous
value of 250 km/s/Mpc to 75, which is close to the current accepted value. Sandage
also did studies on globular clusters, calculating their age to be around 25
billion years. This calculation led him to think that the universe did not only
expand, but it expanded and contracted at a period of 80 billion years. He
co-wrote a paper with Donald Lynden-Bell and Olin J. Eggen during his studies
on the formation of galaxies in the early universe. Sandage discovered jets
erupting from the core of the M82 galaxy, likely caused by massive explosions
in the core, and is noted for this discovery. In 1959, Sandage married fellow
astronomer Mary Connelley. They had two sons.
During his career, Sandage
published over five hundred papers. He won many awards over the course of his
career for his work in astronomy, including the notable Bruce Medal in 1975. A
main-belt asteroid was named after him, 9963 Sandage. He actively researched at
the Carnegie Observatory until his death in 2010, at age 84.
