Arp 81 consists of two strongly interacting galaxies about 100 million years after their closest approach. The galaxy on the left is designated NGC 6621 and the right galaxy is NGC 6622. The larger galaxy on the right is greatly gravitationally disturbed by the encounter. A long tail of stars was pulled out of NGC 6622 and extends around and behind both galaxies. Extensive star formation was triggered between the two galaxies resulting in a rich collection of young massive star clusters. Arp 81 lies in the constellation of Draco and is approximately 300 million light-years from the Earth.
The image above was assembled with data obtained from the Hubble Legacy Archive. Two filtered images were used for the red and blue channels. These were imaged using filters of F814W for red, F450W for blue. An image consisting of a combination of all available filters was used for the green and luminance channels. This image is classified in the Hubble Legacy Archive as a detection, or white light, image. The color image was created as a standard LRGB image.
1Based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA).