Contribution Contributed Talk
Sulfur chemistry in Class 0 disks and jets with ALMA
While there have been numerous studies of the disk and jet chemistry in evolved T Tauri stars, observations of the jet-disk system in protostars are very difficult due to their embedded nature and to the occurrence of numerous other kinematical components in the circumstellar region (cavities of swept-up material, infalling envelope, static ambient cloud).
I will show how to exploit the combination of the ALMA capabilities and the emission of the sulfur-bearing molecules to simultaneously probe for the first time the forming disk and the jet base in the HH 212 Sun-like protostellar system. SO and SO2 lines turn out to be effective tracers of the collimated and fast molecular jet in the inner few hundreds AU from the protostar. Their abundances indicate that from 1% to 40% of elemental sulfur is converted into SO and SO2 due to shocks in the jet and/or to ambipolar diffusion at the wind base. On the other hand, the SO abundance in the disk is found to be 3 − 4 orders of magnitude larger than in evolved protoplanetary disks around Class II sources. The observed SO enhancement may be produced in the accretion shock at the envelope-disk interface or in the shocks occuring in the disk spirals caused by gravitational instabilities if the disk is partly gravitationally unstable.