Saturday, March 1, 2008

Happy Birthday George Abell

Astronomer George Abell (1927 – 1983) was born 81 years ago today. He had a short, yet remarkable career in the world of astronomy.

As a Caltech graduate student in the 1950s, George Abell was one of the principle observers on the National Geographic Palomar Observatory Sky Survey, the first detailed photographic survey of the northern skies. Performed using the Palomar 48-inch Schmidt Telescope (now known as the Samuel Oschin Telescope), images were captured on large (14-inches on a side), square photographic plates that each covered an area of sky 12 times the width of the full moon.

Abell used the data from the survey to produce the first major catalog of clusters of galaxies. His catalog included thousands of galaxy clusters and it the basic reference in this field. It served as the one of the starting points for observational cosmology. He also showed how the brightness of certain galaxies within a cluster could be used to determine the distance to the galaxy cluster, allowing astronomers to map the large scale structure of the universe.

Here is a sky-survey image of a portion of Abell 2151, also known as the Hercules Cluster. The cluster is around 500 million light years distant and is part of the larger Hercules Supercluster.

Abell also studied the planetary nebulae that were revealed by the sky survey. Along with Peter Goldreich he correctly concluded that planetary nebulae evolve directly from red giant stars.

Here’s a sky-survey image of the planetary nebula now known as Abell 39. It is located about 7,000 light years away in the constellation of Hercules.

In addition to his astronomical work George Abell was a noted educator and popularizer of astronomy.

George Abell was honored by having an asteroid, 3449 Abell, named for him. The asteroid was discovered at Palomar Observatory by Eleanor Helin and S. J. “Bobby” Bus.

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