     APOD: 2018 January 23 - Ribbons and Pearls of Spiral Galaxy NGC 1398

                         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 23
                                      [2]
                Ribbons and Pearls of Spiral Galaxy NGC 1398
                Image Credit: European Southern Observatory [3]

Explanation: Why do some spiral galaxies have a ring around the center? Spiral
galaxy NGC 1398 [4]  not only has a ring [5]  of pearly stars, gas and dust
[6]  around its center, but a bar [7]  of stars and gas  across  its center,
and spiral arms that appear like ribbons farther out. The featured image [8]
was taken with ESO [9] 's Very Large Telescope [10]  at the Paranal
Observatory [11]  in Chile [12] and resolves this grand spiral [13]  in
impressive detail. NGC 1398 [14]  lies about 65 million light years [15]
distant, meaning the light we see today left this galaxy when dinosaurs were
disappearing [16]  from the Earth [17] . The photogenic galaxy is visible with
a small telescope toward the constellation of the Furnace (Fornax [18] ). The
ring near the center [19]  is likely an expanding density wave [20]  of star
formation, caused either by a gravitational encounter with another galaxy [21]
, or by the galaxy's own gravitational asymmetries.

                    Tomorrow's picture: almost frogs [22]

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    Authors & editors: Robert Nemiroff [34] (MTU [35] ) & Jerry Bonnell [36]
                                  (UMCP [37] )
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Site notes:
  [1] archivepix.html
  [2] image/1801/NGC1398_ESO_3416.jpg
  [3] http://www.eso.org/
  [4] https://en.wikipedia.org/wiki/NGC_1398
  [5] ap170710.html
  [6] ap030706.html
  [7] ap160109.html
  [8] https://www.eso.org/public/images/potw1801a/
  [9] http://www.eso.org/
  [10] http://www.eso.org/public/usa/teles-instr/paranal-observatory/vlt/
  [11] https://www.youtube.com/watch?v=k_LwlwJWZN0
  [12] https://en.wikipedia.org/wiki/Chile
  [13] ap171226.html
  [14] http://adsabs.harvard.edu/abs/1995ApJ...447..159M
  [15]
https://www.grc.nasa.gov/www/k-12/Numbers/Math/Mathematical_Thinking/
how_long_is_a_light_year.htm
  [16]
https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_extinction_event
  [17] https://solarsystem.nasa.gov/planets/earth
  [18] https://en.wikipedia.org/wiki/Fornax
  [19] ap170807.html
  [20] https://en.wikipedia.org/wiki/Density_wave_theory
  [21] ap130514.html
  [22] ap180124.html
  [23] ap180122.html
  [24] archivepix.html
  [25] lib/apsubmit2015.html
  [26] lib/aptree.html
  [27] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  [28] calendar/allyears.html
  [29] /apod.rss
  [30] lib/edlinks.html
  [31] lib/about_apod.html
  [32] http://asterisk.apod.com/discuss_apod.php?date=180123
  [33] ap180124.html
  [34] http://www.phy.mtu.edu/faculty/Nemiroff.html
  [35] http://www.phy.mtu.edu/
  [36] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  [37] http://www.astro.umd.edu/
  [38] lib/about_apod.html#srapply
  [39] https://www.nasa.gov/about/highlights/HP_Privacy.html
  [40] https://astrophysics.gsfc.nasa.gov/
  [41] https://www.nasa.gov/
  [42] https://www.nasa.gov/centers/goddard/
  [43] http://www.mtu.edu/
