EVAPORATION OF GRAIN-SURFACE SPECIES BY SHOCK WAVES IN A PROTOPLANETARY DISK
Aota et al
Recent Atacama Large Millimeter/submillimeter Array observations of young protostellar objects detected warm SO emission, which could be associated with a forming protostellar disk. In order to investigate if such warm gas can be produced by accretion shock onto the forming disk, we calculate the sputtering and thermal desorption of various grain-surface species in one-dimensional shock waves. We find that thermal desorption is much more efficient than the sputtering in the post-shock region. While H2O can be thermally desorbed, if the accretion velocity is larger than 8 km s–1 with the pre-shock gas number density of 109 cm–3, SO is desorbed if the accretion velocity gsim2 km s–1 and gsim4 km s–1, with the pre-shock density of 109 cm–3 and 108 cm–3, respectively. We also find that the column density of hydrogen nuclei in warm post-shock gas is N warm ~ 1021 cm–2.