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 July 17
    [2]A star surrounded by orange shells and arcs sit in the center of a
    dark starfield. Galaxies from the distant universe can be seen around
    the edges. Please see the explanation for more detailed information.

                    Shells and Arcs around Star CW Leonis
   Image Credit: [3]ESA, [4]NASA, [5]Hubble, [6]T. Ueta ([7]U. Denver), H.
                                Kim ([8]KASI)

   Explanation: What's happening around this star? No one is sure. [9]CW
   Leonis is the closest [10]carbon star, a star that appears orange
   because of atmospheric carbon dispersed from [11]interior nuclear
   fusion. But [12]CW Leonis also appears engulfed in a gaseous
   carbon-rich nebula. What causes the nebula's [13]complexity is unknown,
   but its geometry of [14]shells and arcs are surely [15]intriguing. The
   [16]featured image by the [17]Hubble Space Telescope details this
   complexity. The low surface gravity of carbon [18]stars enhances their
   ability to expel [19]carbon and carbon compounds into space. Some of
   this carbon ends up forming [20]dark [21]dust that is commonly seen in
   the nebulas of [22]young star-forming regions and the [23]disks of
   galaxies. Humans and all Earth-based [24]life are carbon-based, and at
   least some of [25]our carbon was likely once circulating in the
   atmospheres of near-death stars like [26]carbon stars.

                   Tomorrow's picture: telescopes and sky
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    Authors & editors: [38]Robert Nemiroff ([39]MTU) & [40]Jerry Bonnell
                                 ([41]UMCP)
          NASA Official: Phillip Newman [42]Specific rights apply.
              [43]NASA Web Privacy Policy and Important Notices
                A service of: [44]ASD at [45]NASA / [46]GSFC,
                         [47]NASA Science Activation
                           & [48]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2307/CwLeo_Hubble_960.jpg
   3. https://www.esa.int/
   4. https://www.nasa.gov/
   5. https://esahubble.org/
   6. https://science.du.edu/about/faculty-directory/toshiya-ueta
   7. https://science.du.edu/
   8. https://www.kasi.re.kr/
   9. https://en.wikipedia.org/wiki/CW_Leonis
  10. https://en.wikipedia.org/wiki/Carbon_star
  11. https://en.wikipedia.org/wiki/Carbon#Formation_in_stars
  12. https://youtu.be/KstINjrRovE
  13. https://ui.adsabs.harvard.edu/abs/2015EAS....71...87W/abstract
  14. https://apod.nasa.gov/apod/ap221013.html
  15. https://www.intermountainpet.com/hubfs/Blog_Images/Dogs-tilting-their-heads.jpg
  16. https://hubblesite.org/contents/media/images/2021/059/01FJW7YS4R5WJNFY1H3VTF56EZ
  17. https://www.nasa.gov/mission_pages/hubble/about
  18. https://spaceplace.nasa.gov/sun-compare/
  19. https://periodic.lanl.gov/6.shtml
  20. https://apod.nasa.gov/apod/ap230129.html
  21. https://astronomy.swin.edu.au/cosmos/d/Dust+Grain
  22. https://apod.nasa.gov/apod/ap230110.html
  23. https://apod.nasa.gov/apod/ap120311.html
  24. https://astrobiology.com/2016/09/where-did-carbon-come-from-for-life-on-earth.html
  25. https://apod.nasa.gov/apod/ap230108.html
  26. https://skyandtelescope.org/astronomy-blogs/carbon-stars-will-make-see-red1203201401/
  27. https://apod.nasa.gov/apod/ap230716.html
  28. https://apod.nasa.gov/apod/archivepix.html
  29. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  30. https://apod.nasa.gov/apod/lib/aptree.html
  31. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  32. https://apod.nasa.gov/apod/calendar/allyears.html
  33. https://apod.nasa.gov/apod.rss
  34. https://apod.nasa.gov/apod/lib/edlinks.html
  35. https://apod.nasa.gov/apod/lib/about_apod.html
  36. https://asterisk.apod.com/discuss_apod.php?date=230717
  37. https://apod.nasa.gov/apod/ap230718.html
  38. http://www.phy.mtu.edu/faculty/Nemiroff.html
  39. http://www.phy.mtu.edu/
  40. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  41. http://www.astro.umd.edu/
  42. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  43. https://www.nasa.gov/about/highlights/HP_Privacy.html
  44. https://astrophysics.gsfc.nasa.gov/
  45. https://www.nasa.gov/
  46. https://www.nasa.gov/centers/goddard/
  47. https://science.nasa.gov/learners
  48. http://www.mtu.edu/