ABOUT THIS IMAGE:

To celebrate the 100 Hours of Astronomy, ESO is sharing two stunning images of unusual galaxies, both belonging to the Sculptor group of galaxies. The images of NGC 55 and NGC 7793, obtained at two of ESO's observatories at La Silla and Paranal in Chile, illustrate the beauty of astronomy.

As part of the International Year of Astronomy 2009 Cornerstone project, 100 Hours of Astronomy, the ambitious "Around the World in 80 Telescopes" event is a unique live webcast over 24 hours, following night and day around the globe to some of the most advanced observatories on and off the planet. To provide a long-lasting memory of this amazing world tour, observatories worldwide are revealing wonderful, and previously unseen, astronomical images. For its part, ESO is releasing outstanding pictures of two galaxies, observed with telescopes at the La Silla and Paranal observatories.

This second image shows another galaxy belonging to the Sculptor group. NGC 7793 has a chaotic spiral structure, unlike the class of grand-design spiral galaxies to which our Milky Way belongs. The image shows how difficult it is to identify any particular spiral arm in these chaotic structures, although it is possible to guess at a general rotating pattern. NGC 7793 is located about 12.5 million light-years from us.

From Wikipedia:

NGC 7793 is a flocculent spiral galaxy about 12.7 million light-years away in the constellation Sculptor. It was discovered in 1826 by James Dunlop.

NGC 7793 is one of the brightest galaxies within the Sculptor Group, a group of galaxies in the constellation of the same name. The group itself is an elongated, loosely bound group of galaxies with the Sculptor Galaxy (NGC 253) and its companion galaxies forming a tightly-bound core of galaxies near the center.

On March 25, 2008, SN 2008bk was discovered in NGC 7793. At apparent magnitude 12.5, it became the 2nd brightest supernova of 2008. The progenitor of this supernova was a Red Supergiant, observed only 547 days prior to the explosion.

Jets from a black hole named P13 power a large nebula named S26 in the outer spiral of this galaxy. Recently, the mass of P13 was determined to be less than 15 solar masses, and its companion star is estimated to be around 20 solar masses. The two orbit each other in 64 days. Based on this estimate, P13 is stripping material away from a nearby star about ten times faster than was previously believed to be physically possible. If correct, this observation would show flaws in theories that a black hole's mass and rate of consumption are a fixed relationship.