Galaxies Collide

A sampling of some of the 59 new images captured by the Hubble Space Telescope and released by NASA Thursday, April 24, 2008, of colliding galaxies that make up the largest collection of Hubble images ever released by NASA. As this astonishing array of images of interacting galaxies illustrates, galaxy collisions produce a remarkable variety of intricate structures. Interacting galaxies are found throughout the Universe.

This Hubble image released by NASA Thursday, April 24, 2008, shows Arp 302, which consists of a pair of very gas-rich spiral galaxies in their early stages of interaction: VV 340A is seen edge-on to the left and VV 340B face-on at right. An enormous amount of infrared light is radiated by the gas from massive stars that are forming at a rate similar to the most vigorous giant star-forming regions in our own Milky Way.

This image shows a pair of interacting galaxies consisting of NGC 5754, the large spiral on the top and NGC 5752, the smaller companion in the bottom left corner of the image. The contrasting reactions of the two galaxies to their interaction are due to their differing masses and sizes. The photos were released to mark the Hubble Space Telescope's 18th launch anniversary.

This image shows the NGC 6670 pair of overlapping edge-on galaxies. Scientists believe that NGC 6670 has already experienced at least one close encounter and is now in the early stages of a second. The nuclei of the two galaxies are approximately 50,000 light-years apart. NGC 6670 glows in the infrared with more than a hundred billion times the luminosity of our Sun and is thought to be entering a starburst phase.

This image shows NGC 5331, a pair of interacting galaxies beginning to hold their arms. There is a blue trail which appears in the image flowing to the right of the system. NGC 5331 is very bright in the infrared, with about a hundred billion times the luminosity of the Sun. It is located in the constellation Virgo, the Maiden, about 450 million light-years away from Earth.

This image shows Arp 148, the 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 center 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.

This image displays a beautiful pair of interacting spiral galaxies with swirling arms. The smaller of the two, dubbed LEDA 62867 and positioned to the left of the frame, seems to be safe for now, but will probably be swallowed by the larger spiral galaxy; NGC 6786, right, eventually. There is already some disturbance visible in both components. A supernova was seen to explode in the large spiral in 2004.

This image shows NGC 520, the product of a collision between two disc galaxies that started 300 million years ago. It exemplifies the middle stages of the merging process: the discs of the parent galaxies have merged together, but the nuclei have not yet coalesced. NGC 520 is one of the brightest galaxy pairs on the sky, and can be observed with a small telescope toward the constellation of Pisces, the Fish.

This image shows IC 1623, an interacting galaxy system that is very bright when observed in the infrared. One of the two galaxies has a substantial amount of warm and dense gas. Warm and dense gas is also found in the overlap region connecting the two nuclei. Observations support the notion that it is approaching the final stage of its merger, when a violent central inflow of gas will trigger intense starburst activity.

This image shows a Hubble view of Arp 272, a remarkable collision between two spiral galaxies, NGC 6050 and IC 1179, and is part of the Hercules Galaxy Cluster, located in the constellation of Hercules. The galaxy cluster is part of the Great Wall of clusters and superclusters, the largest known structure in the Universe. The two spiral galaxies are linked by their swirling arms.

This image shows Arp 81, a strongly interacting pair of galaxies, seen about 100 million years after their closest approach. It consists of NGC 6621, to the left, and NGC 6622, to the right. NGC 6621 is the larger of the two, and is a very disturbed spiral galaxy. The encounter has pulled a long tail out of NGC 6621 that has now wrapped behind its body. The collision triggered extensive star formation between the two.