Closer look at the magnetic field structure around the fragment at t = 1300 Myr. It is clear that the magnetic field traces the filamentary structure, with opposite/unstructured magnetic fields occurring in the low-density region around it. This is similar to the magnetic field structure formed from the GI-dynamo simulations of Riols & Latter (2019), which due to magnetic flux redistribution generates opposite radial mean fields within and outside the spiral arm. In addition, we can see that there is a strong field reversal in the gap in front of the fragment.