Hoag-type galaxies: A New One on me!

Discussion in 'Astronomy, Exobiology, & Cosmology' started by paddoboy, Jan 4, 2017.

  1. paddoboy Valued Senior Member

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    Researchers get first look at new, extremely rare galaxy
    January 4, 2017

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    The left panel shows a false-color image of PGC 1000714. The right panel shows a B-I color index map that reveals both the outer ring (blue) and diffuse inner ring (light green). Credit: Ryan Beauchemin
    Approximately 359 million light-years away from Earth, there is a galaxy with an innocuous name (PGC 1000714) that doesn't look quite like anything astronomers have observed before. New research provides a first description of a well-defined elliptical-like core surrounded by two circular ringsā€”a galaxy that appears to belong to a class of rarely observed, Hoag-type galaxies. This work was done by scientists at the University of Minnesota Duluth and the North Carolina Museum of Natural Sciences.

    "Less than 0.1% of all observed galaxies are Hoag-type galaxies," says Burcin Mutlu-Pakdil, lead author of a paper on this work and a graduate student at the Minnesota Institute for Astrophysics, University of Minnesota Twin Cities and University of Minnesota Duluth. Hoag-type galaxies are round cores surrounded by a circular ring, with nothing visibly connecting them. The majority of observed galaxies are disc-shaped like our own Milky Way. Galaxies with unusual appearances give astronomers unique insights into how galaxies are formed and change.

    Read more at: http://phys.org/news/2017-01-extremely-rare-galaxy.html#jCp
     
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  3. paddoboy Valued Senior Member

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    http://mnras.oxfordjournals.org/content/466/1/355

    A photometric study of the peculiar and potentially double ringed, non-barred galaxy: PGC 1000714


    Abstract
    We present a photometric study of PGC 1000714, a galaxy resembling Hoag's Object with a complete detached outer ring, that has not yet been described in the literature. Since the Hoag-type galaxies are extremely rare and peculiar systems, it is necessary to increase the sample of known objects by performing the detailed studies on the possible candidates to derive conclusions about their nature, evolution and systematic properties. We therefore performed surface photometry of the central body by using the archival near-UV, infrared data and the new optical data (BVRI). This current work has revealed for the first time an elliptical galaxy with two fairly round rings. The central body follows well a r1/4 light profile, with no sign of a bar or stellar disc. By reconstructing the observed spectral energy distribution, we recover the stellar population properties of the central body and the outer ring. Our work suggests different formation histories for the galaxy components. Possible origins of the galaxy are discussed, and we conclude that a recent accretion event is the most plausible scenario that accounts for the observational characteristic of PGC 1000714.
     
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  5. danshawen Valued Senior Member

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    An axially oriented collision between a left handed spiral galaxy with a right handed spiral galaxy might create a Hoag object. It would be rare.
     
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