NGC 7253A and NGC 7253B (aka Arp 278)
Interacting Galaxies - Supernova 2002 jg

Supernova 2002 jg:

• Discovered November 23rd, 2002, by KAIT and Mike Schwartz.
• Magnitude at discovery: 16.8
• Type: Ia
• The supernova is magnitude 15.98 in the Kopernik image.

NGC 7253 is a pair of interacting spiral galaxies that was once considered a merging group of several galaxies. The bright knots of star formation throughout both galaxies led to this conclusion, but astronomers now believe that this system is a classic case of two spirals in collision leading to both becoming 'starburst galaxies'. There is a compact radio source in the core of NGC 7253A, and a faint, diffuse radio source coincides with NGC 7253B.

This pair is included in Arp’s catalog of unusual galaxies as ARP 278. Arp noted about this group: "Diffuse material between galaxies, many internal absorption lanes......"

Using the red shift data from the “NASA Extra-galactic Data Base(NED)”, (and a Hubble Constant of 62 Km per sec., per Megaparsec), one can calculate a rough distance estimate of 238 million light years for the NGC 7253 pair; At that distance the diameter of NGC 7253A would be 115,000 light years, and that of NGC 7253B would be 110,000 light years.

NGC 7253A (ARP 278) Magnitude: 14.4 Constellation: Pegasus RA: 22h 19m 29.0s Dec: +29° 23' 11" Epoch 2000 Size (mins): 1.7' x 0.5' Classification: Barred Spiral ??? Description in the NGC:        "Very faint, westward extended."

NGC 7253B (ARP 278) Magnitude: 15.0 Constellation: Pegasus RA: 22h 19m 26.3s Dec: +29° 23' 53" Epoch 2000 Size (mins): 1.6' x 0.5' Classification: Spiral ??? Deep Sky Field Guide:     "Spiral Galaxy (uncertain); double system, in contact with NGC 7253A."

Click below to

George Normandin, KAS

December 10th, 2002