A Keplerian disk around a Class 0 source: ALMA observations of VLA1623A
Rotationally supported disks are key in the star formation process. The questions of when do they form and what factors influence or hinder their formation have been studied, but are largely unanswered. Observations of early stage YSOs are needed to probe disk formation. VLA1623 is a triple non-coeval protostellar system, with a weak magnetic field, whose Class 0 component, VLA1623A, shows a disk-like structure in continuum with signatures of rotation in line emission (Murillo & Lai 2013). Here we aim to determine whether this structure is in part or in whole a rotationally supported disk, i.e. a Keplerian disk, and what are its characteristics. ALMA Cycle 0 Early Science 1.3 mm continuum and C18O (2-1) observations in the extended configuration are presented here and used to perform an analysis of the disk-like structure using PV diagrams and thin disk modelling with the addition of foreground absorption. We conclude that VLA1623A, a very young Class 0 source, presents a Keplerian disk with an outer radius Rout = 180 AU. The weak magnetic fields and recent fragmentation in this region of ρ Ophiuchus may have played a role in the formation of the disk.