Korean VLBI Network (KVN)

2014 Special Seminar:

08/26/2014   09/11/2014   11/11/2014   12/17/2014  

2:00pm, 17 Dec. (Wed) 2014
Ms. Nadia Murillo (Max Planck Institute for Extraterrestrial Physics) : (host : Dr. Kee-Tae Kim)
331-2, Jangyongsil hall
The physical and temperature structure of the disk-envelope interface: ALMA DCO+ observations of VLA1623

The structure of the transition from the envelope to the rotationally supported disk, the disk-envelope interface, is poorly studied.

This is due to instrumental limitations and lack of disk detections in early embedded protostellar systems.

To probe this region, both CO isotopologues and freeze-out tracers are needed. VLA1623A is a deeply embedded Class 0 protostar with a confirmed rotationally supported disk extending out to at least 150 AU.

This makes VLA1623A an ideal target to study the disk-envelope interface.

We model ALMA Cycle 0 observations of DCO+ and C18O towards VLA1623A. An analytic model using a simple chemical network coupled with radial density and temperature profiles is used as input for line radiative transfer modelling.

Observations show the DCO+ emission towards VLA1623A to border the C18O emission tracing the disk.

Modelling results indicate that a decrease in temperature is needed to reproduce the observed DCO+ emission, while an increase in density reproduces the C18O emission well.

Our results show that the physical structure of the disk-envelope interface differs from the rest of the envelope, highlighting the drastic impact that the disk has on the envelope and temperature structure. Finally, our results show that DCO+ is an excellent tracer of cold temperature regions.

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