A submillimetre survey of the kinematics of the Perseus molecular cloud
  - III. Clump kinematics
  We explore the kinematics of continuum clumps in the Perseus molecular cloud,
derived from C18O J=3-2 data. Two populations are examined, identified using
the automated algorithms CLFIND and GAUSSCLUMPS on existing SCUBA data. The
clumps have supersonic linewidths with distributions which suggest the C18O
line probes a lower-density 'envelope' rather than a dense inner core. Similar
linewidth distributions for protostellar and starless clumps implies protostars
do not have a significant impact on their immediate environment. The proximity
to an active young stellar cluster seems to affect the linewidths: those in
NGC1333 are greater than elsewhere. In IC348 the proximity to the old IR
cluster has little influence, with the linewidths being the smallest of all. A
virial analysis suggests that the clumps are bound and close to equipartition.
In particular, the starless clumps occupy the same parameter space as the
protostars, suggesting they are true stellar precursors and will go on to form
stars. We also search for ordered C18O velocity gradients across the face of
each core, usually interpreted as rotation. We note a correlation between the
directions of the identified gradients and outflows across protostars,
indicating we may not have a purely rotational signature. The fitted gradients
are larger than found in previous work, probably as a result of the higher
resolution of our data and/or outflow contamination. These gradients, if
interpreted solely in terms of rotation, suggest that rotation is not
dynamically significant. Furthermore, derived specific angular momenta are
smaller than observed in previous studies, centred around j~0.001 km/s pc,
which indicates we have identified lower levels of rotation, or that the C18O
J=3-2 line probes conditions significantly denser and/or colder than n~10^5 per
cc and T~10 K.
