                        Astronomy Picture of the Day

    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 December 26
     The featured image shows a star inside a symmetric but complex and
    multi-colored nebula which is all surrounded by a faint blue nebula.
          Please see the explanation for more detailed information.

                   NGC 6164: Dragon's Egg Nebula and Halo
                  Image Credit & Copyright: Russell Croman

   Explanation: The star at the center created everything. Known as the
   Dragon's Egg, this star -- a rare, hot, luminous O-type star some 40
   times as massive as the Sun -- created not only the complex nebula (NGC
   6164) that immediately surrounds it, but also the encompassing blue
   halo. Its name is derived, in part, from the region's proximity to the
   picturesque NGC 6188, known as the fighting Dragons of Ara. In another
   three to four million years the massive star will likely end its life
   in a supernova explosion. Spanning around 4 light-years, the nebula
   itself has a bipolar symmetry making it similar in appearance to more
   common planetary nebulae - the gaseous shrouds surrounding dying
   sun-like stars. Also like many planetary nebulae, NGC 6164 has been
   found to have an extensive, faint halo, revealed in blue in this deep
   telescopic image of the region. Expanding into the surrounding
   interstellar medium, the material in the blue halo was likely expelled
   from an earlier active phase of the O-star. NGC 6164 lies 4,200
   light-years away in the southern constellation of the Carpenter's
   Square (Norma).

                   Tomorrow's picture: all the way around
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