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.

                              2024 February 12
     [2]The image shows a dark field filled with stars and a diffuse red
      nebula running across horizontally. In the field are two circular
   objects that are bright, light colored. The lower object is larger and
   encircled in a blue glow. Please see the explanation for more detailed
                                information.

                      HFG1 & Abell 6: Planetary Nebulae
    Image Credit & Copyright: [3]Julien Cadena & [4]Mickael Coulon; Text:
                   [5]Natalia Lewandowska ([6]SUNY Oswego)

   Explanation: [7]Planetary nebulae like [8]Heckathorn-Fesen-Gull 1
   (HFG1) and [9]Abell 6 in the constellation [10]Cassiopeia are remnants
   from the last phase of a [11]medium sized star like our [12]Sun. In
   spite of their shapes, planetary nebulae have [13]nothing in common
   with actual planets. Located in the bottom left part of the
   [14]featured photo, HFG1 was created by the [15]binary star system V664
   Cas, which consists of a [16]white dwarf star and a [17]red giant star.
   Both stars orbit their [18]center of mass over about [19]half an Earth
   day. Traveling with the entire nebula at a speed about 300 times faster
   than the fastest train on Earth, V664 Cas generates a [20]bluish arc
   shaped [21]shock wave. The wave interacts most strongly with the
   surrounding [22]interstellar medium in the areas where the arc is
   brightest. After roughly [23]10,000 years, planetary nebulae become
   invisible due to a lack of [24]ultraviolet light being emitted by the
   [25]stars that create them. Displaying [26]beautiful shapes and
   structures, planetary nebulae are [27]highly desired objects for
   astrophotographers.

                       Tomorrow's picture: a wolf moon
     __________________________________________________________________

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    Authors & editors: [39]Robert Nemiroff ([40]MTU) & [41]Jerry Bonnell
                                 ([42]UMCP)
          NASA Official: Amber Straughn; [43]Specific rights apply.
              [44]NASA Web Privacy Policy and Important Notices
                A service of: [45]ASD at [46]NASA / [47]GSFC,
                         [48]NASA Science Activation
                           & [49]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2402/Hfg1Abell6_CadenaCoulon_6140.jpg
   3. https://www.astrobin.com/users/JulienCadena/
   4. https://www.instagram.com/mickael_coulon_astrophoto/
   5. https://www.oswego.edu/physics/natalia-lewandowska
   6. https://www.oswego.edu/physics/
   7. https://en.wikipedia.org/wiki/Planetary_nebula
   8. https://www.sternwarte-baerenstein.de/hfg1-abell6-en.html
   9. https://in-the-sky.org/data/object.php?id=Abell_6
  10. https://en.wikipedia.org/wiki/Cassiopeia_(constellation)
  11. https://imagine.gsfc.nasa.gov/educators/lifecycles/SC_main_p1.html
  12. https://science.nasa.gov/sun
  13. https://images.squarespace-cdn.com/content/v1/5b631cba5b409b413bb3a633/1533669968141-15YL8HF098WAOR8RYKFD/A-dog-looking-confused-and-surprised.jpg
  14. https://www.facebook.com/ZwoDesignAstronomyCameras/posts/802324015256448
  15. https://science.nasa.gov/universe/stars/multiple-star-systems/
  16. https://apod.nasa.gov/apod/ap231224.html
  17. https://apod.nasa.gov/apod/ap110408.html
  18. https://spaceplace.nasa.gov/barycenter/en/
  19. https://www.astro.oma.be/en/gaia-observes-a-cosmic-clock-inside-a-large-planetary-nebula/
  20. https://www.astronomersdoitinthedark.com/index.php?c=145&p=571
  21. https://apod.nasa.gov/apod/ap240104.html
  22. https://en.wikipedia.org/wiki/Interstellar_medium
  23. http://koreascience.or.kr/article/JAKO200502637762045.page
  24. https://science.nasa.gov/ems/10_ultravioletwaves
  25. https://en.wikipedia.org/wiki/Star
  26. https://apod.nasa.gov/apod/ap240107.html
  27. https://skynews.ca/hfg1-abell-6-by-dan-kusz/
  28. https://apod.nasa.gov/apod/ap240211.html
  29. https://apod.nasa.gov/apod/archivepix.html
  30. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  31. https://apod.nasa.gov/apod/lib/aptree.html
  32. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  33. https://apod.nasa.gov/apod/calendar/allyears.html
  34. https://apod.com/feed.rss
  35. https://apod.nasa.gov/apod/lib/edlinks.html
  36. https://apod.nasa.gov/apod/lib/about_apod.html
  37. https://asterisk.apod.com/discuss_apod.php?date=240212
  38. https://apod.nasa.gov/apod/ap240213.html
  39. http://www.phy.mtu.edu/faculty/Nemiroff.html
  40. http://www.phy.mtu.edu/
  41. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  42. http://www.astro.umd.edu/
  43. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  44. https://www.nasa.gov/about/highlights/HP_Privacy.html
  45. https://astrophysics.gsfc.nasa.gov/
  46. https://www.nasa.gov/
  47. https://www.nasa.gov/centers/goddard/
  48. https://science.nasa.gov/learners
  49. http://www.mtu.edu/