The mm-colors of a young binary disk system in the Orion Nebula Cluster

TL;DR

This study uses new 7 mm EVLA observations of a binary disk system in Orion to compare dust grain sizes and test dust evolution models, revealing unexpected differences between the disks.

Contribution

It provides the first detailed millimeter spectral index measurements of individual disks in a binary system, challenging existing dust evolution predictions.

Findings

The less dense, hotter disk hosts larger grains, contrary to models.

Differences in disk viscosity or radial solid motions may explain observations.

Method demonstrates how high-resolution millimeter data can test dust evolution theories.

Abstract

We present new EVLA continuum observations at 7 mm of the 253-1536 binary disk system in the Orion Nebula Cluster. The measured fluxes were combined with data in the sub-mm to derive the millimeter spectral index of each individual disk component. We show how these observations can be used to test the models of dust evolution and early growth of solids in protoplanetary disks. Our analysis indicates that the disk with lower density and higher temperature hosts larger grains than the companion disk. This result is the opposite of what predicted by the dust evolution models. The models and observational results can be reconciled if the viscosity $\alpha$-parameter differs by more than a factor of ten in the two disks, or if the distribution of solids in the disks is strongly affected by radial motions. This analysis can be applied to future high-angular resolution observations of young disks with EVLA and ALMA to provide even stronger observational constraints to the models of dust evolution in protoplanetary disks.