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.

                                 2022 May 8
   [2]The featured image shows the spiral galaxy NGC 1512 as taken by the
     Hubble Space Telescope. The galaxy shows two rings surrounding its
      center. Please see the explanation for more detailed information.

                   Spiral Galaxy NGC 1512: The Inner Rings
          Image Credit: [3]NASA, [4]ESA, [5]Hubble Space Telescope

   Explanation: Most galaxies don't have any rings -- why does this galaxy
   have two? To begin, the bright band near [6]NGC 1512's center is a
   [7]nuclear ring, a ring that surrounds the galaxy center and glows
   brightly with recently [8]formed stars. Most stars and accompanying gas
   and [9]dust, however, orbit the galactic center in a ring much further
   out -- here seen near the image edge. This ring is called,
   [10]counter-intuitively, the inner ring. If you look closely, you will
   see this [11]the inner ring connects ends of a diffuse [12]central bar
   that runs horizontally across the galaxy. These ring structures are
   thought to be caused by [13]NGC 1512's own asymmetries in a drawn-out
   process called [14]secular evolution. The [15]gravity of these galaxy
   asymmetries, including the bar of stars, cause gas and dust to fall
   from the inner ring to the nuclear ring, enhancing this ring's rate of
   [16]star formation. [17]Some spiral galaxies also have a third ring --
   an outer ring that [18]circles the galaxy even further out.

                     Tomorrow's picture: martian eclipse
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    Authors & editors: [30]Robert Nemiroff ([31]MTU) & [32]Jerry Bonnell
                                 ([33]UMCP)
          NASA Official: Phillip Newman [34]Specific rights apply.
              [35]NASA Web Privacy Policy and Important Notices
                A service of: [36]ASD at [37]NASA / [38]GSFC
                           & [39]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2205/NGC1512inner_Hubble_5413.jpg
   3. https://www.nasa.gov/
   4. https://www.esa.int/
   5. https://www.nasa.gov/mission_pages/hubble/story/index.html
   6. https://en.wikipedia.org/wiki/NGC_1512
   7. https://apod.nasa.gov/apod/ap170710.html
   8. https://en.wikipedia.org/wiki/Star_formation
   9. https://apod.nasa.gov/apod/ap030706.html
  10. https://ru.fishki.net/picsw/112007/29/ugol/ugol_012.jpg
  11. https://ui.adsabs.harvard.edu/abs/2017ApJS..230...14M/abstract
  12. https://apod.nasa.gov/apod/ap200611.html
  13. https://esahubble.org/news/heic1712/
  14. https://ui.adsabs.harvard.edu/abs/2004ARA&A..42..603K/abstract
  15. https://spaceplace.nasa.gov/what-is-gravity/en/
  16. https://starchild.gsfc.nasa.gov/docs/StarChild/universe_level2/stars.html
  17. https://apod.nasa.gov/apod/ap150526.html
  18. https://www.nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-orbit-58.html
  19. https://apod.nasa.gov/apod/ap220507.html
  20. https://apod.nasa.gov/apod/archivepix.html
  21. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  22. https://apod.nasa.gov/apod/lib/aptree.html
  23. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  24. https://apod.nasa.gov/apod/calendar/allyears.html
  25. https://apod.nasa.gov/apod.rss
  26. https://apod.nasa.gov/apod/lib/edlinks.html
  27. https://apod.nasa.gov/apod/lib/about_apod.html
  28. http://asterisk.apod.com/discuss_apod.php?date=220508
  29. https://apod.nasa.gov/apod/ap220509.html
  30. http://www.phy.mtu.edu/faculty/Nemiroff.html
  31. http://www.phy.mtu.edu/
  32. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  33. http://www.astro.umd.edu/
  34. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  35. https://www.nasa.gov/about/highlights/HP_Privacy.html
  36. https://astrophysics.gsfc.nasa.gov/
  37. https://www.nasa.gov/
  38. https://www.nasa.gov/centers/goddard/
  39. http://www.mtu.edu/