NGC 5257 and NGC 5258
Arp 240 is an astonishing galaxy pair, composed of spiral galaxies of similar mass and size, NGC 5257 (left) and NGC 5258 (right). The galaxies are visibly interacting with each other via a bridge of dim stars connecting the two galaxies. Both galaxies harbour supermassive black holes in their centres and are actively forming new stars in their discs. Arp 240 is located in the constellation Virgo, approximately 300 million light-years away, and is the 240th galaxy in Arp's Atlas of Peculiar Galaxies.
With the exception of a few foreground stars from our own Milky Way all the objects in this image are galaxies.
This image is part of a large collection of 59 images of merging galaxies taken by the Hubble Space Telescope and released on the occasion of its 18th anniversary on 24 April 2008.