When Galaxies Collide

Hubble image of Arp 148, the result of a galactic collision. Credit: NASA/ESA, STScI, and the Hubble Heritage Team. Processing by Jason Major.

Here’s a cosmic curiosity: Arp 148, aka “Mayall’s Object,” the aftermath of a collision between two galaxies. It’s located 450 million light-years away in the constellation Ursa Major (of which the Big Dipper is part.) This is my color-composite of Hubble images originally acquired in April 2007 in optical and near-infrared light.

According to the description on ESA’s Hubble site (which features the agency’s official processed version):

Arp 148 is the staggering aftermath of an encounter between two galaxies, resulting in a ring-shaped galaxy and a long-tailed companion. The collision between the two parent galaxies produced a shockwave effect that first drew matter into the centre and then caused it to propagate outwards in a ring. The elongated companion perpendicular to the ring suggests that Arp 148 is a unique snapshot of an ongoing collision. Infrared observations reveal a strong obscuration region that appears as a dark dust lane across the nucleus in optical light.

Arp 148 was discovered by American astronomer Nicholas U. Mayall of the Lick Observatory on March 13, 1940, using the Crossley reflector. When first discovered, Mayall’s Object was described as a peculiar nebula, shaped like a question mark. (Wikipedia)

The name comes from Halton Arp, an American astronomer known for his 1966 catalog Atlas of Peculiar Galaxies, which includes what are now known to be interacting and merging galaxies.