Monday, March 26, 2012 - 11:00am
"Can we trust CO emission as a probe of the densities and temperatures of molecular clouds?"
Abstract. I will present results from a set of simulations of the gas in molecular clouds, performed using a fully dynamical 3D model of magnetised turbulence coupled to a simplified chemical network. The aim here is to quantify the range of temperatures and densities present in the gas containing most of the CO in clouds. CO is distributed across a range of different environments in molecular clouds, from well-shielded cold regions, to warmer, poorly-shielded regions where the CO abundance is very small. This later component represents a significant fraction of the volume of most molecular clouds.We find that most of the CO is located at densities over 10^3 cm^-3 where the temperature is roughly 10-40 K independently of the mean density, metallicity and UV field strength.