page_title: NGC 6621
hierarchical_section_title: NGC 6621
caption_attribution_description: NGC 6621/2 (VV 247, Arp 81) is a strongly interacting pair of galaxies, seen about 100 million years after their closest approach. It consists of NGC 6621 (to the right) and NGC 6622 (to the left). 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 has also triggered extensive star formation between the two galaxies. Scientists believe that Arp 81 has a richer collection of young massive star clusters than the notable Antennae galaxies (which are much closer than Arp 81). The pair is located in the constellation of Draco, approximately 300 million light-years away from Earth. Arp 81 is the 81st galaxy in Arp's Atlas of Peculiar 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 24th April 2008. About the object Object name NGC 6621, NGC 6622, VV 247, Arp 81, VII Zw 778, KPG 534A Object description Interacting Galaxies Position (J2000) 18 12 54.70+68 21 49.0 Constellation Draco Distance 300 million light-years (100 million parsecs) About the data Data description The Hubble image was created using HST data from proposal 7467: W. Keel (University of Alabama, Tuscaloosa) Instrument WFPC2 Exposure date(s) March 15, 1999 Exposure time 1.4 hours Filters F435W (B) and F814W (I)
context_page_description: NGC 6621 is an interacting spiral galaxy in the constellation Draco. It lies at a distance of circa 260 million years. NGC 6621 interacts with NGC 6622, with their closest approach having taken place about 100 million years before the moment seen now. The pair was discovered by Edward D. Swift and Lewis A. Swift on June 2, 1885. Originally NGC 6621 was assigned to the southeast galaxy, but now it refers to the northern one. NGC 6621 and NGC 6622 are included in the Atlas of Peculiar Galaxies as Arp 81 in the category "spiral galaxies with large high surface brightness companions".
  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 at the north behind its body. The collision has also triggered extensive star formation between the two galaxies. The most intense star formation takes place in the region between the two nuclei, where a large population of luminous clusters, also known as super star clusters, has been observed. At this region is observed the most tidal stress. Many large clusters are also observed in the tail and the nucleus of NGC 6621.
context_section_description: NGC 6621 is an interacting spiral galaxy in the constellation Draco. It lies at a distance of circa 260 million years. NGC 6621 interacts with NGC 6622, with their closest approach having taken place about 100 million years before the moment seen now. The pair was discovered by Edward D. Swift and Lewis A. Swift on June 2, 1885. Originally NGC 6621 was assigned to the southeast galaxy, but now it refers to the northern one. NGC 6621 and NGC 6622 are included in the Atlas of Peculiar Galaxies as Arp 81 in the category "spiral galaxies with large high surface brightness companions".
  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 at the north behind its body. The collision has also triggered extensive star formation between the two galaxies. The most intense star formation takes place in the region between the two nuclei, where a large population of luminous clusters, also known as super star clusters, has been observed. At this region is observed the most tidal stress. Many large clusters are also observed in the tail and the nucleus of NGC 6621. The brightest and bluest clusters are less than 100 million years old, with the youngest being less than 10 million years old. The side of the galaxy further from the companion features noticeably less star formation activity.
  NGC 6621 is characterised as a luminous infrared galaxy, with its infrared luminosity being 1011.24 L☉. NGC 6621 contributes nearly all of the radio and far infrared flux of the pair. When observed in H-alpha, the centre of the galaxy has two bright sources separated by 3 arcseconds, with the southwest being brighter while the northeastern one coincides with the nucleus of NGC 6621.
  One supernova has been detected in NGC 6621, SN 2010hi. It was discovered on September 1.893 (UTC) at magnitude 18.0 lying 30" east and 4" north of the center of the galaxy.
caption: Hubble Space Telescope image of NGC 6621 (center) and NGC 6622 (left)
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