BIMA N2H+ 1-0 mapping observations of L183 -- fragmentation and spin-up
  in a collapsing, magnetized, rotating, pre-stellar core
  We have used the Berkeley-Illinois-Maryland Array (BIMA) to make deep N2H+
1-0 maps of the pre-stellar core L183, in order to study the spatial and
kinematic substructure within the densest part of the core. Three spatially and
kinematically distinct clumps are detected, which we label L183-N1, L183-N2 and
L183-N3. L183-N2 is approximately coincident with the submillimetre dust peak
and lies at the systemic velocity of L183. Thus we conclude that L183-N2 is the
central dense core of L183. L183-N1 and 3 are newly-discovered fragments of
L183, which are marked by velocity gradients that are parallel to, but far
stronger than, the velocity gradient of L183 as a whole, as detected in
previous single-dish data. Furthermore, the ratio of the large-scale and
small-scale velocity gradients, and the ratio of their respective size-scales,
are consistent with the conservation of angular momentum for a rotating,
collapsing core undergoing spin-up. The inferred axis of rotation is parallel
to the magnetic field direction, which is offset from its long axis, as we have
seen in other pre-stellar cores. Therefore, we propose that we have detected a
fragmenting, collapsing, filamentary, pre-stellar core, rotating about its
B-field, which is spinning up as it collapses. It will presumably go on to form
a multiple protostellar system.
