Testing a New Model of Embedded Protostellar Disks Against Observation: The Majority of Orion Class 0/I Disks Are Likely Warm, Massive, and Gravitationally Unstable

TL;DR

This study introduces a parametrized model for embedded protostellar disks, fitting observations to reveal most Orion Class 0/I disks are warm, massive, and likely gravitationally unstable, challenging previous assumptions.

Contribution

The paper presents a new model that estimates disk properties from dust emission, accounting for optical thickness and internal heating, providing more accurate disk mass and temperature estimates.

Findings

Most Orion Class 0/I disks are warm and massive.

Disks have a star-to-disk mass ratio around 1.

Disks are likely gravitationally unstable.

Abstract

We formulate a parametrized model of embedded protostellar disks and test its ability to estimate disk properties by fitting dust-continuum observations. The main physical assumptions of our model are motivated by a recent theoretical study of protostellar disk formation; these assumptions include that the disk should be marginally gravitationally unstable, and that the dominant dust heating mechanism is internal accretion heating instead of external protostellar irradiation. These assumptions allow our model to reliably estimate the disk mass even when the observed emission is optically thick and to self-consistently determine disk (dust) temperature. Using our model to fit multi-wavelength observations of 156 disks in the VANDAM Orion survey, we find that the majority (57%) of this sample can be fit well by our model. Using our model, we produce new estimates of Orion protostellar disk properties. We find that these disks are generally warm and massive, with a typical star-to-disk mass ratio $M_{\rm d}/M_\star = \mathcal O(1)$ in Class 0/I. We also discuss why our estimates differ from those in previous studies and the implications of our results on disk evolution and fragmentation.