Thursday, October 15, 2009

Barnard’s Little Galaxy

On Wednesday, The European Southern Observatory (ESO) released a new image of NGC 6822, also known as Barnard’s Galaxy. It is classified as an irregular dwarf galaxy because of its unusual shape and relatively small size--if a galaxy can be classified in any way as small. NGC 6822 is located about 1.63 million light-years away, in the direction of the constellation Sagittarius. Because of its relative closeness, NGC 6822 is classified as a member of the Local Group of galaxies—our galactic neighborhood. The galaxy was discovered in 1881 by American amateur-turned-professional astronomer Edward Emerson Barnard (1857 – 1932) using a six-inch refractor telescope. Studying strange galaxies like NGC 6822 help astronomers understand how galaxies interact, evolve and occasionally gobble up each other, leaving behind these galactic crumbs.


NGC 6822, Barnard’s Galaxy, as recorded by the Wide Field Imager attached to the 2.2-meter MPG/ESO telescope at ESO’s La Silla Observatory in northern Chile. Image Credit: ESO

An irregular dwarf galaxy is a dwarf galaxy that lacks any apparent structure or a uniform shape. In recent times astronomers have gradually placed higher and higher importance in the study of irregular dwarf galaxies as a method of understanding the evolution of galaxies in general, because there are so many examples near to our own galaxy. Their study can help us understand important issues such as the occurrence of galactic winds, the chemical enrichment of the interstellar and intergalactic media, and the photometric—brightness—evolution of galaxies. In addition, their low level of evolution, as implied by their low amounts of metals and their high amounts of gases, makes them the most similar to early galaxies and, therefore, the most useful for research into what primordial galaxies may have been like. Some have also suggested that these nearby irregular dwarf galaxies are similar to the many faint blue galaxies seen in deep galaxy counts. To learn more about the ESO’s latest image release, and to learn more about the ESO, check out these links:

NGC 6822, Barnard’s Galaxy, as recorded by the Wide Field Imager attached to the 2.2-meter MPG/ESO telescope at ESO’s La Silla Observatory in northern Chile. Image Credit: ESO
http://www.eso.org/gallery/v/ESOPIA/Galaxies/phot-38a-09-fullres.tif.html

European Southern Observatory
http://www.eso.org/

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