Magnetic field strength map for the collapsing core W51 e2, calculated with the polarization-intensity gradient method (Koch, Tang and Ho, 2012, ApJ 747(1), 79, 2012-03).
The magnetic field strength,
color wedge in units of mG, is increasing toward the center with additional features across
the core. The white segments are magnetic field orientations, rotated by 90 degrees from their
orginally detected orientations from dust polarization.