The Evolution of the Snow Line in a Protoplanetary Disk

THE EVOLUTION OF THE SNOW LINE IN A PROTOPLANETARY DISK

Authors:

Zhang et al

Abstract:

We study the evolutionary behavior of the snow line with a time-dependent disk model that includes the mass influx onto the disk from the collapse of the progenitor cloud core. We are able to investigate the evolution of the snow line during the disk formation and early evolution. We find that the radius of the snow line in a disk first increases with time, reaches a maximum, ${{R}_{{\rm max} }}$, and then decreases with time. The mass influx in our model inherits the progenitor core properties and we quantitatively illustrate the relationship between the behavior of the snow line and the core properties. We find that the mass influx onto the disk becomes dilute for high core angular momentum and that surface density near the snow line decreases. Thus viscosity heating decreases and ${{R}_{{\rm max} }}$ becomes small. When the angular momentum is low, the amount of material falling onto the disk is small and thus the surface density is small. This limits the value of ${{R}_{{\rm max} }}$. We find that the maximum value of ${{R}_{{\rm max} }}$ is $17.4\;{\rm AU}$ for the core mass $=1\ {{M}_{}}$. We suggest that diffusion of water vapor to ${{R}_{{\rm max} }}$ makes ${{R}_{{\rm max} }}$ a preferred location for gas giant planet formation. Water inside ${{R}_{{\rm max} }}$ is substantially depleted due to diffusion. The observed lack of cold water vapor in protoplanetary disks by Herschel might be related to the depletion of water inside ${{R}_{{\rm max} }}$.