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   CHRS: LATIN-1 2   
                           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.   
      
                                   2025 July 22   
         A nearly circular nebula with two rings is shown. The outer ring   
      appears orange while while the inner rings is more complex and appears   
          blue. Please see the explanation for more detailed information.   
      
                           A Double Detonation Supernova   
       Image Credit: ESO, P. Das et al.; Background stars (NASA/Hubble): K.   
                                    Noll et al.   
      
      Explanation: Can some supernovas explode twice? Yes, when the first   
      explosion acts like a detonator for the second. This is a leading   
      hypothesis for the cause of supernova remnant (SNR) 0509-67.5. In this   
      two-star system, gravity causes the larger and fluffier star to give up   
      mass to a smaller and denser white dwarf companion. Eventually the   
      white dwarf's near-surface temperature goes so high that it explodes,   
      creating a shock wave that goes both out and in -- and so triggers a   
      full Type Ia supernova near the center. Recent images of the SNR   
      0509-67.5 system, like the featured image from the Very Large Telescope   
      in Chile, show two shells with radii and compositions consistent with   
      the double detonation hypothesis. This system, SNR 0509-67.5 is also   
      famous for two standing mysteries: why its bright supernova wasn't   
      noted 400 years ago, and why no visible companion star remains.   
      
                     Tomorrow's picture: rock being vaporized   
        __________________________________________________________________   
      
          Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)   
               NASA Official: Amber Straughn Specific rights apply.   
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