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.

                               2020 August 31

                      SS 433: Binary Star Micro-Quasar
              Animation Credit: DESY, Science Communication Lab

   Explanation: SS 433 is one of the most exotic star systems known. Its
   unremarkable name stems from its inclusion in a catalog of Milky Way
   stars which emit radiation characteristic of atomic hydrogen. Its
   remarkable behavior stems from a compact object, a black hole or
   neutron star, which has produced an accretion disk with jets. Because
   the disk and jets from SS 433 resemble those surrounding supermassive
   black holes in the centers of distant galaxies, SS 433 is considered a
   micro-quasar. As illustrated in the animated featured video based on
   observational data, a massive, hot, normal star is locked in orbit with
   the compact object. As the video starts, material is shown being
   gravitationally ripped from the normal star and falling onto an
   accretion disk. The central star also blasts out jets of ionized gas in
   opposite directions - each at about 1/4 the speed of light. The video
   then pans out to show a top view of the precessing jets producing an
   expanding spiral. From even greater distances, the dissipating jets are
   then visualized near the heart of supernova remnant W50. Two years ago,
   SS 433 was unexpectedly found by the HAWC detector array in Mexico to
   emit unusually high energy (TeV-range) gamma-rays. Surprises continue,
   as a recent analysis of archival data taken by NASA's Fermi satellite
   find a gamma-ray source -- separated from the central stars as shown --
   that pulses in gamma-rays with a period of 162 days - the same as SS
   433's jet precession period - for reasons yet unknown.

       Teachers & Students: Ideas for utilizing APOD in the classroom.
                     Tomorrow's picture: salted asteroid
     __________________________________________________________________

       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.


--- MBSE BBS v1.0.7.18 (GNU/Linux-x86_64)