Fig. 1: Simulation of the initial emergence of a twisted magnetic tube.
From: Direct evidence that twisted flux tube emergence creates solar active regions
(a) displays field lines at \(t\) = 2500 s, with a slice indicating the horizontal photospheric boundary (red plane) where the magnetic field is measured. The \(x\)-, \(y\)- and \(z\)-directions are indicated. The colour bar indicates (dimensionless) magnetic field strength (to convert to physical units, see Methods: Numerical simulation details). Darker colours (mainly blue) indicate weaker field strengths and lighter colours (green and yellow) indicate stronger field strengths. In (b), the emergence accumulation \({L}_{{{{{\rm{emerge}}}}}}\) (yellow line), the braiding accumulation \({L}_{{{{{\rm{braid}}}}}}\) (red line), and the total winding accumulation \(L={L}_{{{{{\rm{emerge}}}}}}+{L}_{{{{{\rm{braid}}}}}}\) (blue line) are displayed. \(5\times {L}_{{{{{\rm{braid}}}}}}\) is displayed on the figure in order to convey clearly how \({L}_{{{{{{\rm{braid}}}}}}}\) develops in time.
