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

Abstract

We formulate a parameterized 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 estimate reliably the disk mass even when the observed emission is optically thick and to determine self-consistent disk (dust) temperatures. Using our model to fit multiwavelength observations of 163 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 d / M ⋆ =  ( 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.