The Magnetic Fields of Spiral Galaxy M77.

Can magnetic fields help tell us how spiral galaxies form and evolve? To find out, the HAWC+ instrument on NASA's airborne ( 747 ) SOFIA observatory observed nearby spiral galaxy M77 . HAWC+ maps magnetism by observing polarized infrared light emitted by elongated dust grains rotating in alignment with the local magnetic field . The HAWC+ image shows that magnetic fields do appear to trace the spiral arms in the inner regions of M77 , arms that likely highlight density waves in the inflowing gas, dust and stars caused by the gravity of the galaxy's oval shape. The featured picture superposes the HAWC+ image over diffuse X-ray emission mapped by NASA's NuSTAR satellite and visible light images taken by Hubble and the SDSS . M77 is located about 47 million light years away toward the constellation of the Sea Monster ( Cetus ).