Radio continuum observations of Class I protostellar disks in Taurus: constraining the greybody tail at centimetre wavelengths

TL;DR

This study uses 1.8 cm radio observations of young stellar objects in Taurus to analyze dust grain growth and estimate disk masses, revealing larger grains and potential for giant planet formation.

Contribution

It provides new constraints on the long-wavelength tail of the greybody spectrum in protostellar disks, highlighting the importance of radio data for disk mass estimation.

Findings

Spectra consistent with large dust grain populations (beta ≈ 0.26)

Disk masses from radio data are systematically higher than from sub-mm data

Some disks meet criteria for giant planet formation

Abstract

We present deep 1.8 cm (16 GHz) radio continuum imaging of seven young stellar objects in the Taurus molecular cloud. These objects have previously been extensively studied in the sub-mm to NIR range and their SEDs modelled to provide reliable physical and geometrical parametres.We use this new data to constrain the properties of the long-wavelength tail of the greybody spectrum, which is expected to be dominated by emission from large dust grains in the protostellar disk. We find spectra consistent with the opacity indices expected for such a population, with an average opacity index of beta = 0.26+/-0.22 indicating grain growth within the disks. We use spectra fitted jointly to radio and sub-mm data to separate the contributions from thermal dust and radio emission at 1.8 cm and derive disk masses directly from the cm-wave dust contribution. We find that disk masses derived from these flux densities under assumptions consistent with the literature are systematically higher than those calculated from sub-mm data, and meet the criteria for giant planet formation in a number of cases.