The stellar surface is depicted in white. The star is spherically symmetric, and initially at areal radius Rs / M = 4.
The initial magnetic field is chosen to be momentary static, in a dipole configuration. Henceforth we will show the view on the right to view the evolution in the meridional plane, exploiting axisymmetry.
We draw field lines by drawing contours in Aφ, the φ component of the magnetic vector potential. The contour values are chosen in the maximal time slicing coordinate system, such that the initial interior field lines in a meridional plane are spaced evenly along the equator. We identify the fluid elements on the star's surface to which these lines connect. For all t > 0 we continue to draw the field lines which pass through these fluid elements, consistent with flux freezing. We also choose additional contour values to track disjoint field lines that arise in the vacuum exterior.