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.

                               2021 January 18

                    The Medulla Nebula Supernova Remnant
                  Image Credit & Copyright: Russell Croman

   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
   130-hours of exposure with two small telescopes in New Mexico, USA, to
   create the featured image.

                    Tomorrow's picture: moon and planets
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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