This image captures a pair of Arp objects in the constellation of Cetus at a declination of -13 degrees. This is one of the closest pairings of Arp objects in the entire Arp catalog of 338 objects. Both of these objects are Astrobin Debut Objects. Each Arp object contains two galaxies.

Arp 144 is the interesting pair of magnitude 14.5 galaxies at image center. The elliptical galaxy (lower left of pair) is NGC 7829, while the spiral galaxy is NGC 7828. These galaxies are located about 260 million light years away. Each galaxy is about 30 arc-seconds wide in our apparent view, which corresponds to a diameter for each of about 50,000 light years. Dr. Arp categorized this in his category of Elliptical Galaxies – Material Emanating from Elliptical Galaxies. An intriguing title to be sure.

Arp 144 is fascinating to me. Star streams connect the 2 galaxies. As is typical, the elliptical is fairly undisturbed. But the spiral galaxy is a wonderful mess. I can’t make much sense of it. A stellar-like blue section is likely a star cluster. Just to its left is the remnant of a dust band. The remains of the disk extend above and curl back down to the right. It is not hard to imagine these 2 galaxies becoming a large elliptical in the future.

Arp 51 is the face-on spiral galaxy to the lower right, with a very faint companion on the arm just above and left of the core. Arp 51 may be my least favorite Arp object. Like the galaxies of Arp 141, the main galaxy is about 30 arc-seconds wide. There is no distance information available on either the main galaxy or the companion. My guess, based on the detail in the spiral structure, is that it is about twice as far away as Arp 144, which would put this galaxy at about 100,000 light years in diameter. Dr. Arp categorized this in his category of Spiral Galaxies – Small, High Surface Brightness Companions on Arms. For more of a description of this object as well as a comparison mouseover, please go here: Arp 51 .