Looking Up: The 'Superman Galaxy' spinning faster than a speeding bullet

Submitted photo
Photo taken by Ted Wolfe using his telescope in Naples.

Submitted photo Photo taken by Ted Wolfe using his telescope in Naples.

M83 is a magnificent spiral galaxy that lies well down in the southern skies. It's popular name is the "Superman Galaxy" because its overall design looks like the "S" on Superman's shirt.

Its about 15 million light years away in the constellation of Hydra, the sea monster. Fittingly, due to its far southern position in the night sky, it was first observed through a telescope at the Cape of Good Hope by the Abbe Nicholas la Caille in 1751. Much later the great comet hunter, Charles Messier, picked it up while sweeping for comets with his telescope down near the southern horizon from Paris. Since it was so far south he could only see it, in his words, "with great difficulty." He gave it the 83rd spot on his famous list of interesting objects. Hence the name: M83.

Today we can easily reach it with telescope and camera from Naples, which is one of the southern most observing sites in the continental United States. Unlike Messier we can clearly capture its dramatic appearance. It literally seems to whirl in a counter-clockwise fashion before our eyes.

M83's shape is defined by the two major spiral arms that start out from its center. Smaller arms branch out here and there but the two main ones are the real clock winders for this galaxy.

Note the colors that are strewn across the face of the galaxy. The red areas harbor the nebula that give birth to new stars, while the bright blue regions contain the young, very hot, blue-white giant stars that populate the galaxy. The central region of the galaxy, as with all spirals, contains the senior citizen stars of the galaxy, and it glows with the tell tale yellowish hue associated with older stars.

So why are spiral arms important to a galaxy?

Imagine that a spiral galaxy is like a pancake you have just started to make in your skillet. Now imagine that the pancake batter is spinning — like a galaxy does in space. The spinning produces a pinwheel effect, radiating out from the center. The spiral arms moving through the pancake batter are like rotating waves in the pinwheel. The pancake batter builds up along the waves. In fact, the spiral arms are really "density waves."

These density waves move around the galaxy. As gas and dust encounter the waves, they are compressed and new stars are formed from the compressed material. So the spiral arms are critical to star formation.

The "S" that forms the shape of the Superman Galaxy is also the engine that generates the very life blood of the galaxy — its stars.

Ted is a member of the Everglades Astronomical Society. Organized in 1981 it serves the Naples community providing information in all aspects of amateur astronomy. Its goals include educating the general public, school children, and other groups to the wonders of the universe. The Society meets at 7 p.m. every second Tuesday of the month at the Norris Center (public invited). Regular viewing visits to a special, dark sky site in the Everglades are held each month, allowing the general public to observe the night sky through telescopes, under pristine conditions. For more information visit the website at: http://naples.net/clubs/eas.


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