  Massive stars, multiple stellar systems and clusters are born from the
gravitational collapse of massive dense gaseous clumps, and the way these
systems form strongly depends on how the parent clump fragments into cores
during collapse. Numerical simulations show that magnetic fields may be the key
ingredient in regulating fragmentation. Here we present ALMA observations at
~0.25'' resolution of the thermal dust continuum emission at ~278 GHz towards a
turbulent, dense, and massive clump, IRAS 16061-5048c1, in a very early
evolutionary stage. The ALMA image shows that the clump has fragmented into
many cores along a filamentary structure. We find that the number, the total
mass and the spatial distribution of the fragments are consistent with
fragmentation dominated by a strong magnetic field. Our observations support
the theoretical prediction that the magnetic field plays a dominant role in the
fragmentation process of massive turbulent clump.
