                        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 March 30

                        Animation: Odd Radio Circles
     Credits: Illustration: Sam Moorfield; Data: CSIRO, HST (HUDF), ESA,
                                    NASA;
      Image: J. English (U. Manitoba), EMU, MeerKAT, DES (CTIO); Text:
                               Jayanne English

   Explanation: What do you call a cosmic puzzle that no one expected to
   see? In this case, Odd Radio Circles, aka ORCs. ORC-1 typifies the
   enigmatic five objects, only visible at radio frequencies, that were
   serendipitously discovered in 2019 using the new Australian SKA
   Pathfinder radio array. The final image in the featured video uses 2021
   data from the South African MeerKAT array to reveal more detail. The
   radio data, assigned turquoise colors, are combined with a Dark Energy
   Survey optical/IR map. The animated artist’s illustration explores just
   one idea about the ORCs’ origins. If two supermassive black holes merge
   in the center of a galaxy, the associated shockwaves could generate
   rings of radio radiation. These grow to fill the video frame. The video
   zooms out so the expansion the ORC can be tracked until it is about a
   million light-years across. Fortunately, the up-coming Square Kilometer
   Array can help test this and other promising scenarios.

                       Tomorrow's picture: open space
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
                NASA Web Privacy Policy and Important Notices
                      A service of: ASD at NASA / GSFC
                             & Michigan Tech. U.

