ALMA Observations of the Very Young Class 0 Protostellar System HH211-mms: A 30 au Dusty Disk with a Disk Wind Traced by SO?

Abstract

HH 211-mms is one of the youngest Class 0 protostellar systems in Perseus, at a distance of ∼235 pc. We have mapped its central region at up to ∼7 au (0.″03) resolution. A dusty disk is seen deeply embedded in a flattened envelope, with an intensity jump in the dust continuum at ∼350 GHz. It is nearly edge-on and is almost exactly perpendicular to the jet axis. It has a size of ∼30 au along the major axis. It is geometrically thick, indicating that the (sub)millimeter light-emitting grains have yet to settle to the midplane. Its inner part is expected to have transformed into a Keplerian rotating disk with a radius of ∼10 au. A rotating disk atmosphere and a compact rotating bipolar outflow are detected in SO N J  = 8 9  − 7 8 . The outflow fans out from the inner disk surfaces and is rotating in the same direction as the flattened envelope, and hence could trace a disk wind carrying away angular momentum from the inner disk. From the rotation of the disk atmosphere, the protostellar mass is estimated to be ≲50 M Jup . Together with results from the literature, our result favors a model where the disk radius grows linearly with the protostellar mass, as predicted by models of pre-stellar dense core evolution that asymptotes to an r −1 radial profile for both the column density and angular velocity.