The JCMT Legacy Survey of the Gould Belt: a molecular line study of the
  Ophiuchus molecular cloud
  CO, $^{13}$CO and C$^{18}$O ${\it J}$ = 3--2 observations are presented of
the Ophiuchus molecular cloud. The $^{13}$CO and C$^{18}$O emission is
dominated by the Oph A clump, and the Oph B1, B2, C, E, F and J regions. The
optically thin(ner) C$^{18}$O line is used as a column density tracer, from
which the gravitational binding energy is estimated to be $4.5 \times 10^{39}$
J (2282 $M_\odot$ km$^2$ s$^{-2}$). The turbulent kinetic energy is $6.3 \times
10^{38}$ J (320 $M_\odot$ km$^2$ s$^{-2}$), or 7 times less than this, and
therefore the Oph cloud as a whole is gravitationally bound. Thirty protostars
were searched for high velocity gas, with eight showing outflows, and twenty
more having evidence of high velocity gas along their lines-of-sight. The total
outflow kinetic energy is $1.3 \times 10^{38}$ J (67 $M_\odot$ km$^2$
s$^{-2}$), corresponding to 21$\%$ of the cloud's turbulent kinetic energy.
Although turbulent injection by outflows is significant, but does ${\it not}$
appear to be the dominant source of turbulence in the cloud. 105 dense
molecular clumplets were identified, which had radii $\sim$ 0.01--0.05 pc,
virial masses $\sim$ 0.1--12 $M_\odot$, luminosities $\sim$ 0.001--0.1 K~km
s$^{-1}$ pc$^{-2}$, and excitation temperatures $\sim$ 10--50K. These are
consistent with the standard GMC based size-line width relationships, showing
that the scaling laws extend down to size scales of hundredths of a parsec, and
to sub solar-mass condensations. There is however no compelling evidence that
the majority of clumplets are undergoing free-fall collapse, nor that they are
pressure confined.
