Astronomy Picture of the Day

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

                              2023 September 13
    [2]A galaxy with blue spiral arms is seen in the image center in the
     midst of numerous foreground stars. This galaxy is surrounded by a
     white envelope, which was found to be hydrogen gas. Please see the
                 explanation for more detailed information.

                  NGC 4632: Galaxy with a Hidden Polar Ring
   Credit: [3]Jayanne English ([4]U. Manitoba), [5]Nathan Deg ([6]Queen's
   University) & [7]WALLABY Survey, [8]CSIRO/[9]ASKAP, [10]NAOJ/[11]Subaru
             Telescope; Text: [12]Jayanne English (U. Manitoba)

   Explanation: Galaxy NGC 4632 hides a secret from optical telescopes. It
   is surrounded by a ring of cool [13]hydrogen gas orbiting at 90 degrees
   to its spiral disk. Such [14]polar ring galaxies have previously been
   discovered using starlight. However, NGC 4632 is among the first in
   which a [15]radio [16]telescope survey revealed a polar ring. The
   [17]featured composite image combines this gas ring, observed with the
   highly sensitive [18]ASKAP telescope, with optical data from the
   [19]Subaru telescope. Using [20]virtual reality, astronomers separated
   out the gas in the main disk of the galaxy from the ring, and the
   subtle color gradient traces its orbital motion. Why do [21]polar rings
   exist? They could be material [22]pulled from one galaxy as it
   [23]gravitationally interacts with a companion. Or hydrogen gas flows
   along the [24]filaments of the cosmic web and accretes into a ring
   around a galaxy, some of which gravitationally contracts into stars.

                       Tomorrow's picture: open space
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    Authors & editors: [36]Robert Nemiroff ([37]MTU) & [38]Jerry Bonnell
                                 ([39]UMCP)
          NASA Official: Phillip Newman [40]Specific rights apply.
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                A service of: [42]ASD at [43]NASA / [44]GSFC,
                         [45]NASA Science Activation
                           & [46]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2309/PolarRing_Askap_960.jpg
   3. https://jayannecosmoscanvas.wordpress.com/
   4. https://umanitoba.ca/science/physics-and-astronomy
   5. https://nathandeg.com/
   6. https://www.queensu.ca/physics/
   7. https://wallaby-survey.org/
   8. https://www.csiro.au/
   9. https://www.csiro.au/en/about/facilities-collections/ATNF/ASKAP-radio-telescope/
  10. https://www.nao.ac.jp/
  11. https://subarutelescope.org/
  12. http://www2.physics.umanitoba.ca/u/english/
  13. https://periodic.lanl.gov/1.shtml
  14. https://apod.nasa.gov/apod/ap990510.html
  15. https://science.nasa.gov/ems/05_radiowaves
  16. https://public.nrao.edu/telescopes/radio-telescopes/
  17. https://youtu.be/dkMr-D2719w
  18. https://www.csiro.au/en/about/facilities-collections/atnf/askap-radio-telescope
  19. https://subarutelescope.org/
  20. https://images.nasa.gov/details/ARC-1992-AC89-0437-6
  21. https://en.wikipedia.org/wiki/Polar-ring_galaxy
  22. https://www.rover.com/blog/wp-content/uploads/dog-playing-tug.jpg
  23. https://apod.nasa.gov/apod/ap190811.html
  24. https://www.youtube.com/watch?v=c-H3WzaewdY
  25. https://apod.nasa.gov/apod/ap230912.html
  26. https://apod.nasa.gov/apod/archivepix.html
  27. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  28. https://apod.nasa.gov/apod/lib/aptree.html
  29. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  30. https://apod.nasa.gov/apod/calendar/allyears.html
  31. https://apod.nasa.gov/apod.rss
  32. https://apod.nasa.gov/apod/lib/edlinks.html
  33. https://apod.nasa.gov/apod/lib/about_apod.html
  34. https://asterisk.apod.com/discuss_apod.php?date=230913
  35. https://apod.nasa.gov/apod/ap230914.html
  36. http://www.phy.mtu.edu/faculty/Nemiroff.html
  37. http://www.phy.mtu.edu/
  38. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  39. http://www.astro.umd.edu/
  40. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  41. https://www.nasa.gov/about/highlights/HP_Privacy.html
  42. https://astrophysics.gsfc.nasa.gov/
  43. https://www.nasa.gov/
  44. https://www.nasa.gov/centers/goddard/
  45. https://science.nasa.gov/learners
  46. http://www.mtu.edu/