cold CO gas in protoplanetary disks

Abstract

Sublimation temperature of CO is about 20K. CO is considered to be frozon onto dust grains in low-temperature (T < 20K) regions of protoplanetary disks. Dartois et al. (2003), however, estimated the CO temperature to be 13K by observing two rotational transitions of CO in the disk. In this presentation, I will show that the turbulent mixing in the vertical direction can produce observable amount of low-temperature CO.