We explore the kinematic properties of dense continuum clumps in the Perseus molecular cloud , derived from our wide-field C ^ { 18 } O J = 3 \to 2 data across four regions – NGC 1333 , IC348/HH211 , L1448 and L1455 .
Two distinct populations are examined , identified using the automated algorithms clfind ( 85 clumps ) and gaussclumps ( 122 clumps ) on existing SCUBA 850 µm data .
These kinematic signatures are compared to the clumps ’ dust continuum properties .
We calculate each clump ’ s non-thermal linewidth and virial mass from the associated C ^ { 18 } O J = 3 \to 2 spectrum .
The clumps have supersonic linewidths , \langle \sigma _ { \mathrm { NT } } / c _ { \mathrm { s } } \rangle = 1.76 \pm 0.09 ( clfind population ) and 1.71 \pm 0.05 ( with gaussclumps ) .
The linewidth distributions suggest the C ^ { 18 } O 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 NGC 1333 are greater than elsewhere .
In IC348 the proximity to the old IR cluster has little influence , with the linewidths being the smallest of all .
The virial analysis suggests that the clumps are bound and close to equipartition , with virial masses similar to the masses derived from the continuum emission .
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 C ^ { 18 } O velocity gradients across the face of each core .
Approximately one third have significant detections , which we mainly interpret in terms of rotation .
However , we note a correlation between the directions of the identified gradients and outflows across the protostars , indicating we may not have a purely rotational signature .
The fitted gradients are in the range { \cal G } = 1 to 16 km s ^ { -1 } pc ^ { -1 } , 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 the rotation is not dynamically significant : the ratios of clump rotational to gravitational energy are \beta _ { \mathrm { rot } } \lesssim 0.02 .
Furthermore , derived specific angular momenta are smaller than observed in previous studies , centred around j \sim 10 ^ { -3 } km s ^ { -1 } pc , which indicates we have identified lower levels of rotation , or that the C ^ { 18 } O J = 3 \to 2 line probes conditions significantly denser and/or colder than n \sim 10 ^ { 5 } cm ^ { -3 } and T \sim 10 K .