Mar 23, 2009

Galaxies In Collision III

Dr. Halton C. Arp published a landmark work in 1966. In this treatise, titled The Atlas Of Peculiar Galaxies, Dr. Arp catalogued and named several hundred strange galaxies, or galaxy-like structures that did not fit the standard types more commonly found in the Universe (spiral, barred spirals, elliptical, amorphous etc.). An online copy of this catalogue, as well as links to a .pdf version, are available from the Caltech website. The preface to this catalogue is very informative. Images of the various galaxies can be found in this online version.
This is another website which compiles instructions so amateur astronomers can view these "Peculiar Galaxies." It also contains a link where you can purchase a beautiful book with color plates of many of Dr. Arp's galaxies.
One of these galaxies has been imaged in more clarity than ever before. It is called Arp 261, and is pictured below.

The image of Arp 261 shows what appears to be a very late-stage of galactic collision, as well as various other interesting objects. Not only are there dozens of galaxies in the field of view, each being far, far beyond Arp 261, as seen from earth, but there are two asteroids from within our own Solar System which happened to travel through the picture frame as this image was being exposed. They are labeled below, and appear as small streaks of red/green/blue. The reason for this color is that three different color filters were used in creating this exposure, and each one "colored" the small trail left by the two asteroids. A seemingly bright star is visible in the lower left-hand corner of the image. This star is contained within our own Milky Way. A very bright supernova is marked in the image below. It went supernova in 1995 and has maintained a very strong luminescence for the past decade! Scientists are curious as to why it is so bright, since supernovas normally flare up and dim down quite rapidly. They suspect that the brightness comes from the ejected star material colliding with very dense interstellar dust clouds, energizing them and causing them to give off continued bright light. Everything else seen in this image is very, very far away.

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