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Southern Pinwheel Galaxy (M83)
Karl Larsen


M83 (also known as the Southern Pinwheel Galaxy, Messier 83, or NGC 5236) is an intermediate spiral galaxy in the constellation Hydra about 15 million light-years away.  It was discovered in 1752 by Nicolas Louis de Lacaille at the Cape of Good Hope.  Since it is situated in the constellation Hydra, it is the southernmost galaxy in Messier’s catalog.  Within its classification as a spiral galaxy, M83 is known as a barred spiral galaxy.  A barred spiral galaxy has a bar-like shape composed by stars cutting across the central nuclear bulge.

Like our own galaxy, the Milky Way, M83 is a typical spiral galaxy consisting of four main parts. Spiral galaxies usually consist of a nuclear bulge, a halo, a disk, and spiral arms.  Spiral galaxies seem usually have a lot of activity going on within their systems.  They usually have old and new stars contained within their systems, as well as new star formation. The newer stars are usually the most easily seen due to their brightness/hotness and these stars compose the spiral arms. This can been seen in the blue spirals of arms. The color blue is due to the hotness of these stars; since they form and burn out quickly the arms are constantly forming and reforming. The red color that is interspersed with the blue is Hydrogen gas waiting to become new stars. The dark areas in between the arms of the galaxy are clouds of dust between the telescope and the galaxy. The yellow color in the center is a grouping of older stars. Clusters of stars are often visible in the outer halos of the spiral galaxies. The reason for the interesting shape of spiral galaxies is because galaxies are constantly rotating discs. A disturbance in this disc creates these spiral patterns. The angular size of M83 is about 513 arc seconds. Its linear size is about 37300 light years.


Austin, Bob. Messier Object 83. N.p., 2007. Web. 12 Apr. 2011. <>.

Bennett, Jeffery, Megan Donahue, Nicholas Schneider, and Mark Voit. The Essential Cosmic Perspective. Second ed. San Francisco, CA: Pearson Education Inc., 2003. 154-58. Print.

Messier 83. Ed. Hartmut Frommert. SEDs, 9 Mar. 2009. Web. 12 Apr. 2011. <>.

Right Ascension (J2000) 13:37:02
Declination (J2000) -29:52:04
Filters used B (Blue), C (Clear), R (Red), V (Green)
Exposure time per filter B, V, and R (300s); C (60s x 5)
Date observed March 23, 2011



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