EPoS Contribution
EPoS Contribution
Observational Evidence for Turbulence Dissipating in Giant Molecular Clouds

Andy Pon
UWO, London, CA
Simulations show that the supersonic turbulence in molecular clouds will dissipate rapidly, on the order of crossing times, if the turbulence is not further driven. We have run models of low velocity shocks in fully molecular conditions to show that CO lines are the most effective lines at removing turbulent energy from a cloud. We also predict that mid-J CO lines, towards regions with interstellar radiation fields of the order of unity, should trace a hot gas component created by the dissipation of turbulent energy. We present observations of low-mass and high-mass star-forming showing signs of just such a hot gas component and discuss the implications of these observations in terms of this shock dissipation framework.
Caption: CO observations towards the Perseus B1-E5 starless clump are shown as the points. The triangles (black) and squares (green) are for the 8 and 3 km / s components detected in the spectra, respectively. The dashed line shows the best fit PDR model, for the ambient unshocked gas, while the dotted line shows the best fit model for the hot, shock heated gas. The solid line shows the combined fit. Note that the CO 6-5 transition has too large of an integrated intensity for the PDR models, such that a hot gas component is required to fit the complete CO SLED.
D. Johnstone, NRC-HIA, CA
M.J. Kaufman, San Jose State U, US
P. Caselli, MPE, DE
R. Plume, U Calgary, CA
F. Fontani, INAF, IT
A. Palau, IRyA, MX
M.J. Butler, MPIA, DE
I. Jiménez-Serra, UCL, GB
J.C. Tan, U Florida, US
Key publication

Suggested Session: Turbulence