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.

                              2019 September 6
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                           Recycling Cassiopeia A
     Image Credit: X-ray - [3]NASA, [4]CXC, SAO; Optical - [5]NASA,STScI

   Explanation: Massive stars in our Milky Way Galaxy live spectacular
   lives. Collapsing from vast cosmic clouds, their nuclear furnaces
   ignite and create heavy elements in their cores. After a few million
   years, the [6]enriched material is blasted back into interstellar space
   where star formation can begin anew. The expanding debris cloud known
   as Cassiopeia A is an example of this final phase of the stellar life
   cycle. Light from the explosion which created this supernova remnant
   would have been first [7]seen in planet Earth's sky about 350 years
   ago, although it took that light about 11,000 years to reach us.
   [8]This false-color image, composed of X-ray and optical image data
   from the Chandra X-ray Observatory and Hubble Space Telescope, shows
   the still hot filaments and knots in the remnant. [9]It spans about 30
   light-years at the estimated distance of Cassiopeia A. High-energy
   X-ray emission from specific elements has been color coded, silicon in
   red, sulfur in yellow, calcium in green and iron in purple, to help
   [10]astronomers explore the recycling of our galaxy's [11]star stuff.
   Still expanding, the outer blast wave is seen in blue hues. [12]The
   bright speck near the center is a neutron star, the incredibly dense,
   collapsed remains of the massive stellar core.

                    Tomorrow's picture: Wolf's dusty cave
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    Authors & editors: [24]Robert Nemiroff ([25]MTU) & [26]Jerry Bonnell
                                 ([27]UMCP)
          NASA Official: Phillip Newman [28]Specific rights apply.
              [29]NASA Web Privacy Policy and Important Notices
                A service of: [30]ASD at [31]NASA / [32]GSFC
                           & [33]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/1909/Chandrafirstlight_0.jpg
   3. https://www.nasa.gov/
   4. http://chandra.harvard.edu/
   5. http://www.stsci.edu/
   6. https://apod.nasa.gov/apod/ap190801.html
   7. http://spider.seds.org/spider/Vars/casA.html
   8. https://chandra.harvard.edu/photo/2019/firstlight/
   9. https://chandra.harvard.edu/photo/2009/casa2/
  10. https://arxiv.org/abs/1111.7316
  11. https://apod.nasa.gov/apod/ap171119.html
  12. https://apod.nasa.gov/apod/ap170501.html
  13. https://apod.nasa.gov/apod/ap190905.html
  14. https://apod.nasa.gov/apod/archivepix.html
  15. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  16. https://apod.nasa.gov/apod/lib/aptree.html
  17. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  18. https://apod.nasa.gov/apod/calendar/allyears.html
  19. https://apod.nasa.gov/apod.rss
  20. https://apod.nasa.gov/apod/lib/edlinks.html
  21. https://apod.nasa.gov/apod/lib/about_apod.html
  22. http://asterisk.apod.com/discuss_apod.php?date=190906
  23. https://apod.nasa.gov/apod/ap190907.html
  24. http://www.phy.mtu.edu/faculty/Nemiroff.html
  25. http://www.phy.mtu.edu/
  26. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  27. http://www.astro.umd.edu/
  28. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  29. https://www.nasa.gov/about/highlights/HP_Privacy.html
  30. https://astrophysics.gsfc.nasa.gov/
  31. https://www.nasa.gov/
  32. https://www.nasa.gov/centers/goddard/
  33. http://www.mtu.edu/