Subj : Daily APOD Report
To   : All
From : Alan Ianson
Date : Mon Oct 17 2022 00:52:30

                        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 October 17

                    X-Ray Rings Around a Gamma Ray Burst
       Image Credit: NASA Swift Obs.; Data: B. Cenko (NASA's GSFC), A.
    Beardmore (U. Leicester) et al.; Processing: J. Miller (U. Michigan)

   Explanation: Why would x-ray rings appear around a gamma-ray burst? The
   surprising answer has little to do with the explosion itself but rather
   with light reflected off areas of dust-laden gas in our own Milky Way
   Galaxy. GRB 221009A was a tremendous explosion -- a very bright
   gamma-ray burst (GRB) that occurred far across the universe with
   radiation just arriving in our Solar System last week. Since GRBs can
   also emit copious amounts of x-rays, a bright flash of x-rays arrived
   nearly simultaneously with the gamma-radiation. In this case, the
   X-rays also bounced off regions high in dust right here in our Milky
   Way Galaxy, creating the unusual reflections. The greater the angle
   between reflecting Milky Way dust and the GRB, the greater the radius
   of the X-ray rings, and, typically, the longer it takes for these
   light-echoes to arrive.

                   Tomorrow's picture: a flowering aurora
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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