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.

                               2021 January 27

                   The Vertical Magnetic Field of NGC 5775
      Image Credit: NRAO, NASA, ESA, Hubble; Processing & Text: Jayanne
                            English (U. Manitoba)

   Explanation: How far do magnetic fields extend up and out of spiral
   galaxies? For decades astronomers knew only that some spiral galaxies
   had magnetic fields. However, after NRAO's Very Large Array (VLA) radio
   telescope (popularized in the movie Contact) was upgraded in 2011, it
   was unexpectedly discovered that these fields could extend vertically
   away from the disk by several thousand light-years. The featured image
   of edge-on spiral galaxy NGC 5775, observed in the CHANG-ES (Continuum
   Halos in Nearby Galaxies) survey, also reveals spurs of magnetic field
   lines that may be common in spirals. Analogous to iron filings around a
   bar magnet, radiation from electrons trace galactic magnetic field
   lines by spiraling around these lines at almost the speed of light. The
   filaments in this image are constructed from those tracks in VLA data.
   The visible light image, constructed from Hubble Space Telescope data,
   shows pink gaseous regions where stars are born. It seems that winds
   from these regions help form the magnificently extended galactic
   magnetic fields.

                   Tomorrow's picture: Messier 66 Close Up
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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