NGC 5257 and NGC 5258, aka Arp 240
Interacting Spiral Galaxies in Virgo

NGC 5257 and NGC 5258 are an interacting pair of spiral galaxies in Virgo. There is a dim bridge of stars connecting the two and both galaxies show signs of massive star formation and both also have Active Galactic Nuclei. This pair is also known as Arp 240.

There are a number of dim background galaxies in the image. The one that is marked "G" is SDSS J133955.93+005217.1, a 17.4 magnitude galaxy that is over 1 billion light years away.

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 355 million light years for this galaxy group.

NGC 5257 Magnitude: 13.5 Constellation: Virgo RA: 13h 39m 53.0s Dec: +00° 50' 29" Epoch 2000 Size (mins): 1.8' x 0.9' Classification: Barred Spiral galaxy, (uncertain), peculiar Deep Sky Field Guide:        "Interacting pair with NGC 5258 at 1.3 arc minutes; very small bright nucleus, narrow spiral arms, bright lens, 0.5x0.4 arc minutes, one arm linking with NGC 5258."	NGC 5258 Magnitude: 13.5 RA: 13h 39m 58.0s Dec: +00° 49' 59" Epoch 2000 Size (mins): 1.6' x 1.1' Classification: Barred Spiral galaxy, (uncertain), peculiar Deep Sky Field Guide:     "Bright complex lens, .03x.02 arc minutes, two main bright smooth arms, a third linking with NGC 5277."
Arp 240 Classification: In Arp's classes "galaxies with appearance of fission, adjacent loops".

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George Normandin, KAS

May 21st, 2002