2014MNRAS.445.1508P

Giant molecular clouds contain supersonic turbulence and magnetohydrodynamic simulations predict that this turbulence should decay rapidly. Such turbulent dissipation has the potential to create a warm (T ∼ 100K) gas component within a molecular cloud. We present observations of the CO J = 5-4 and 6-5 transitions, taken with the Herschel Space Observatory, towards the Perseus B1-East 5 region. We combine these new observations with archival measurements of lower rotational transitions and fit photodissociation region models to the data. We show that Perseus B1-E5 has an anomalously large CO J = 6-5 integrated intensity, consistent with a warm gas component existing within the region. This excess emission is consistent with predictions for shock heating due to the dissipation of turbulence in low-velocity shocks with the shocks having a volume filling factor of 0.15 per cent. We find that B1-E has a turbulent energy dissipation rate of 3.5x10³² erg/s and a dissipation time-scale that is only a factor of 3 larger than the flow crossing time-scale.