                        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.

                                2023 April 24
       A nearly spherical but stringy nebula is shown against a starry
       background. The nebula is colored blue and red. Please see the
                 explanation for more detailed information.

                    The Medulla Nebula Supernova Remnant
                 Image Credit & Copyright: Kimberly Sibbald

   Explanation: What powers this unusual nebula? CTB-1 is the expanding
   gas shell that was left when a massive star toward the constellation of
   Cassiopeia exploded about 10,000 years ago. The star likely detonated
   when it ran out of elements near its core that could create stabilizing
   pressure with nuclear fusion. The resulting supernova remnant,
   nicknamed the Medulla Nebula for its brain-like shape, still glows in
   visible light by the heat generated by its collision with confining
   interstellar gas. Why the nebula also glows in X-ray light, though,
   remains a mystery. One hypothesis holds that an energetic pulsar was
   co-created that powers the nebula with a fast outwardly moving wind.
   Following this lead, a pulsar has recently been found in radio waves
   that appears to have been expelled by the supernova explosion at over
   1000 kilometers per second. Although the Medulla Nebula appears as
   large as a full moon, it is so faint that it took many hours of
   exposure with a telescope in Seven Persons, Alberta, Canada to create
   the featured image.

                     Tomorrow's picture: lunar triomuphe
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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