page_title: Atlas of Peculiar Galaxies
section_title: Galaxies with the appearance of fission
hierarchical_section_title: Atlas of Peculiar Galaxies / List of galaxies in the catalog / Amorphous galaxies / Galaxies with the appearance of fission
caption_attribution_description: NGC 5257/8 (Arp 240) is an astonishing galaxy pair, composed of spiral galaxies of similar mass and size, NGC 5257 and NGC 5258. The galaxies are visibly interacting with each other via a bridge of dim stars connecting the two galaxies, almost like two dancers holding hands while performing a pirouette. Both galaxies harbor supermassive black holes in their centers and are actively forming new stars in their disks. 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 24th April 2008. About the objectObject nameNGC 5257, NGC 5257/8, Arp 240, VV 055, KPG 389Object descriptionInteracting GalaxiesPosition (J2000)13 39 55.68 +00 50 03.9ConstellationVirgoDistance300 million light-years (100 million parsecs)About the dataData descriptionThe Hubble image was created using HST data from proposal 10592: A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)InstrumentACS/WFCExposure date(s)December 20, 2001Exposure time33 minutesFiltersF435W (B) and F814W (I)
context_page_description: The Atlas of Peculiar Galaxies is a catalog of peculiar galaxies produced by Halton Arp in 1966. A total of 338 galaxies are presented in the atlas, which was originally published in 1966 by the California Institute of Technology. The primary goal of the catalog was to present photographs of examples of the different kinds of peculiar structures found among galaxies.
context_section_description: Although the description of the objects in this category implies that the galaxies are separating apart, most of these galaxies are merging. Many of the objects have very pronounced tidal tails and bridges that have formed as a consequence of the interaction. Most objects are in the early stages of the merging process, where the galaxies still appear to have distinct nuclei and distinct (albeit distorted) disks. Among the most notable galaxies in this category are the Antennae Galaxies (NGC 4038 and NGC 4039, Arp 244) and the Mice Galaxies (NGC 4676, Arp 242).
  However, not all of these objects are interacting galaxies.  A few of these galaxies are simply nearby dwarf galaxies with irregular structure.
caption: NGC 5257 and NGC 5258 (Arp 240), interacting pair of spiral galaxies.
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