                        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 May 31

                       Simulation: A Disk Galaxy Forms
   Video Credit: TNG Collaboration, MPCDF, FAS Harvard U.; Music: World's
                     Sunrise (YouTube: Jimena Contreras)

   Explanation: How did we get here? We know that we live on a planet
   orbiting a star orbiting a galaxy, but how did all of this form? Since
   our universe moves too slowly to watch, faster-moving computer
   simulations are created to help find out. Specifically, this featured
   video from the IllustrisTNG collaboration tracks gas from the early
   universe (redshift 12) until today (redshift 0). As the simulation
   begins, ambient gas falls into and accumulates in a region of
   relatively high gravity. After a few billion years, a well-defined
   center materializes from a strange and fascinating cosmic dance. Gas
   blobs -- some representing small satellite galaxies -- continue to fall
   into and become absorbed by the rotating galaxy as the present epoch is
   reached and the video ends. For the Milky Way Galaxy, however, big
   mergers may not be over -- recent evidence indicates that our large
   spiral disk Galaxy will collide and coalesce with the slightly larger
   Andromeda spiral disk galaxy in the next few billion years.

      Open Science: Browse 3,000+ codes in the Astrophysics Source Code
                                   Library
                    Tomorrow's picture: recycling a star
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                           NASA Science Activation
                             & Michigan Tech. U.

