        APOD: 2018 January 10 - NGC 2623: Merging Galaxies from Hubble

                         Astronomy Picture of the Day

    Discover the cosmos! [1] Each day a different image or photograph of our
 fascinating universe is featured, along with a brief explanation written by a
                           professional astronomer.

                                2018 January 10
                                      [2]
                    NGC 2623: Merging Galaxies from Hubble
                Image Credit: ESA [3] / Hubble [4]  & NASA [5]

Explanation: Where do stars form when galaxies collide? To help find out,
astronomers imaged the nearby galaxy merger NGC 2623 [6]  in high resolution
with the Hubble Space Telescope [7] . Analysis of this and other Hubble images
as well as images of NGC 2623 [8]  in infrared light [9]  by the Spitzer Space
Telescope [10] , in X-ray light [11]  by XMM-Newton [12] , and in ultraviolet
light [13]  by GALEX [14] , indicate that two originally spiral galaxies [15]
appear now to be greatly convolved and that their cores have unified into one
active galactic nucleus [16]  (AGN). Star formation continues around this core
near the featured image [17]  center, along the stretched out tidal tail [18]
s visible on either side, and perhaps surprisingly, in an off-nuclear region
on the upper left where clusters [19]  of bright blue stars appear. Galaxy
collisions [20]  can take hundreds of millions of years and take several
gravitationally destructive passes. NGC 2623 [21] , also known as Arp 243 [22]
, spans about 50,000 light years and lies about 250 million light years away
toward the constellation of the Crab (Cancer) [23] . Reconstructing [24]  the
original galaxies and how galaxy mergers [25]  happen is often challenging,
sometimes impossible, but generally important to understanding how our
universe evolved [26] .

                   Tomorrow's picture: pixels in space [27]

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    Authors & editors: Robert Nemiroff [39] (MTU [40] ) & Jerry Bonnell [41]
                                  (UMCP [42] )
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Site notes:
  [1] archivepix.html
  [2] image/1801/Arp243_Hubble_3978.jpg
  [3] http://www.esa.int/
  [4] https://www.spacetelescope.org/
  [5] https://www.nasa.gov/
  [6] https://www.spacetelescope.org/images/potw1742a/
  [7] ap090525.html
  [8] http://server1.sky-map.org/starview?object_type=2&object_id=1856
  [9] https://science.nasa.gov/ems/07_infraredwaves
  [10] http://en.wikipedia.org/wiki/Spitzer_Space_Telescope
  [11] https://science.nasa.gov/ems/11_xrays
  [12] http://en.wikipedia.org/wiki/XMM-Newton
  [13] https://science.nasa.gov/ems/10_ultravioletwaves
  [14] http://en.wikipedia.org/wiki/GALEX
  [15] ap080721.html
  [16] http://en.wikipedia.org/wiki/Active_galactic_nucleus
  [17] https://www.spacetelescope.org/images/potw1742a/
  [18] ap060108.html
  [19] open_clusters.html
  [20] http://www.youtube.com/watch?v=D-0GaBQ494E
  [21] https://www.youtube.com/watch?v=WFyZMJ1viIY
  [22] ap121019.html
  [23] http://en.wikipedia.org/wiki/Cancer_(constellation)
  [24] http://adsabs.harvard.edu/abs/2017A%26A...606A..95C
  [25] ap130514.html
  [26] http://en.wikipedia.org/wiki/Galaxy_formation_and_evolution
  [27] ap180111.html
  [28] ap180109.html
  [29] archivepix.html
  [30] lib/apsubmit2015.html
  [31] lib/aptree.html
  [32] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [33] calendar/allyears.html
  [34] /apod.rss
  [35] lib/edlinks.html
  [36] lib/about_apod.html
  [37] http://asterisk.apod.com/discuss_apod.php?date=180110
  [38] ap180111.html
  [39] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [40] http://www.phy.mtu.edu/
  [41] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [42] http://www.astro.umd.edu/
  [43] lib/about_apod.html#srapply
  [44] https://www.nasa.gov/about/highlights/HP_Privacy.html
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  [48] http://www.mtu.edu/
