http://arxiv.org/abs/1809.00390

Context. Observations of the innermost regions of deeply embedded protostellar cores have shown complicated physical structures as well as a rich chemistry with the existence of complex organic molecules. The protostellar envelopes, outflow and large-scale chemistry of Class 0 and Class I objects have been well-studied, but while previous works have hinted at or found a few Keplerian disks at the Class 0 stage, it remains to be seen if their presence in this early stage is the norm. Likewise, while complex organics have been detected toward some Class 0 objects, their distribution is unknown as they could reside in the hottest parts of the envelope, in the emerging disk itself or in other components of the protostellar system, such as shocked regions related to outflows. Aims. In this work, we aim to address two coupled issues regarding protostars: when rotationally supported disks form around deeply embedded protostars and where complex organic molecules reside in such objects. We wish to observe and constrain the velocity profile of the gas kinematics near the central protostar and determine whether Keplerian motion or an infalling-rotating collapse under angular momentum conservation best explains the observations. The distribution of the complex organic molecules will reveal with which structure they are associated: the hot inner envelope or a possible Keplerian disk. Conclusions. We find that L483 does not harbor a Keplerian disk down to at least 15 au in radius. Instead, the innermost regions of L483 are undergoing a rotating collapse, with the complex organics existing in a hot corino with a radius of ~ 40–60 au. This result highlights that some Class 0 objects contain only very small disks, or none at all, with the complex organic chemistry taking place on scales inside the hot corino of the envelope, in a region larger than the emerging disk.

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S. Jacobsen, J. Jørgensen, J. Francesco, et. al.
Wed, 5 Sep 18
15/133

Comments: 18 pages, 10 figures