Southern Ellipse, AM 0644-741, Ring Galaxy

This image could have imperfections as it’s either historical or reportage.

Unbarred lenticular galaxy, cataloged as AM 0644-741, imaged by the Hubble Space Telescope. Sometimes called "The Southern Ellipse" and a member of the class of so-called "ring galaxies", it lies 300 million light-years away in the direction of the southern constellation Volans. Resembling a diamond-encrusted bracelet, the ring of brilliant blue star clusters wraps around the yellowish nucleus of what was once the center of a normal spiral galaxy. The ring is a region of rampant star formation dominated by young, massive, hot blue stars. The pink regions along the ring are rarefied clouds of glowing hydrogen gas that is fluorescing as it is bombarded with strong ultraviolet light from the blue stars. The ring measures 150, 000 light-year diameter, which larger than the Milky Way. A "ring galaxy" is theorized to form when one galaxy collides with another: the gravitational disruption would cause dust in the galaxy to condense and form stars, and ultimately to expand away from the galaxy, creating a ring. Galactic simulation models suggest that the ring of AM 0644-741 will continue to expand for about another 300 million years, after which it will begin to disintegrate. Released on April 22, 2004, to commemorate the 14th anniversary of Hubble's launch on April 24, 1990 and its deployment from the space shuttle Discovery on April 25, 1990.