The VLA Nascent Disk and Multiplicity Survey: First Look at Resolved Candidate Disks around Class 0 and I Protostars in the Perseus Molecular Cloud

TL;DR

This study presents high-resolution VLA observations of candidate protostellar disks around Class 0 and I sources in Perseus, revealing larger-than-expected early disks that challenge existing magnetic braking models.

Contribution

First detailed dust emission analysis of candidate disks around very young protostars at 12 AU resolution, providing new insights into early disk sizes and structures.

Findings

Candidate disks have radii > 10 AU, larger than some models predict.

Surface density profiles are shallower than those around more evolved disks.

Results suggest early disks may be larger than magnetic braking models allow.

Abstract

We present the first dust emission results toward a sample of seven protostellar disk candidates around Class 0 and I sources in the Perseus molecular cloud from the VLA Nascent Disk and Multiplicity (VANDAM) survey with ~0.05'' or 12 AU resolution. To examine the surface brightness profiles of these sources, we fit the Ka-band 8 mm dust-continuum data in the u,v-plane to a simple, parametrized model based on the Shakura-Sunyaev disk model. The candidate disks are well-fit by a model with a disk-shaped profile and have masses consistent with known Class 0 and I disks. The inner-disk surface densities of the VANDAM candidate disks have shallower density profiles compared to disks around more evolved Class II systems. The best-fit model radii of the seven early-result candidate disks are R_c > 10 AU; at 8 mm, the radii reflect lower limits on the disk size since dust continuum emission is tied to grain size and large grains radially drift inwards. These relatively large disks, if confirmed kinematically, are inconsistent with theoretical models where the disk size is limited by strong magnetic braking to < 10 AU at early times.