page_title: UGC 12591
hierarchical_section_title: UGC 12591
caption_attribution_description: English: This NASA/ESA Hubble Space Telescope image showcases the remarkable galaxy UGC 12591. Classified as an S0/Sa galaxy, UGC 12591 sits somewhere between a lenticular and a spiral. It lies just under 400 million light-years away from us in the westernmost region of the Pisces–Perseus Supercluster, a long chain of galaxy clusters that stretches out for 250 million light-years — one of the largest known structures in the cosmos. The galaxy itself is also extraordinary: it is incredibly massive. The galaxy and its halo together contain several hundred billion times the mass of the Sun; four times the mass of the Milky Way. It also whirls round extremely quickly, rotating at speeds of up to 1.8 million kilometres per hour! Observations with Hubble are helping astronomers to understand the mass of UGC 1259, and to determine whether the galaxy simply formed and grew slowly over time, or whether it might have grown unusually massive by colliding and merging with another large galaxy at some point in its past. Français&#160;: UGC 12591 par le télescope spatial Hubble
context_page_description: UGC 12591 is the second most massive known spiral galaxy, after ISOHDFS 27. It is located about 400 million light years away from the Earth in the constellation Pegasus. In addition, it is the spiral galaxy with the highest known rotational speed of about 500 km/s, almost twice that of our galaxy, the Milky Way.
  The galaxy has a mass estimated at 4 times that of the Milky Way, making it the second of the most massive spiral galaxies known to date.
context_section_description: UGC 12591 is the second most massive known spiral galaxy, after ISOHDFS 27. It is located about 400 million light years away from the Earth in the constellation Pegasus. In addition, it is the spiral galaxy with the highest known rotational speed of about 500 km/s, almost twice that of our galaxy, the Milky Way.
  The galaxy has a mass estimated at 4 times that of the Milky Way, making it the second of the most massive spiral galaxies known to date.
caption: UGC 12591, taken by Hubble
exif: {"Image ImageDescription": "This NASA/ESA Hubble Space Telescope image showcases the remarkable galaxy UGC 12591. Classified as an S0/Sa galaxy, UGC 12591 sits somewhere between a lenticular and a spiral. It lies just under 400 million light-years away from us in the westernmost region of the Pisces\u2013Perseus Supercluster, a long chain of galaxy clusters that stretches out for hundreds of light-years \u2014 one of the largest known structures in the cosmos. The galaxy itself is also extraordinary: it is incredibly massive. The galaxy and its halo together contain several hundred billion times the mass of the Sun; four times the mass of the Milky Way. It also whirls round extremely quickly, rotating at speeds of up to 1.8 million kilometres per hour! Observations with Hubble are helping astronomers to understand the mass of UGC 1259, and to determine whether the galaxy simply formed and grew slowly over time, or whether it might have grown unusually massive by colliding and merging with another large galaxy at some point in its past."}