Grain Growth in the Dust Ring with Crescent around Very Low Mass Star ZZ Tau IRS with JVLA

TL;DR

This study investigates grain growth in the dust ring with a crescent around the very low mass star ZZ Tau IRS using JVLA observations, finding evidence of millimeter-sized grains that could facilitate planet formation.

Contribution

It provides the first evidence of significant grain growth to millimeter sizes in a dust crescent around a very low mass star, highlighting potential for efficient planet formation.

Findings

Detected signals at centimeter wavelengths indicating grain growth.

Estimated maximum grain size in the crescent is >1 mm.

Grain growth suggests potential for efficient planet formation.

Abstract

The azimuthal asymmetries of dust rings in protoplanetary disks such as a crescent around young stars are often interpreted as dust traps, and thus as ideal locations for planetesimal and planet formations. Whether such dust traps effectively promote planetesimal formation in disks around very-low-mass stars (VLM; a mass of $\lesssim$0.2~$M_\odot$) is debatable, as the dynamical and grain growth timescales in such systems are long. To investigate grain growth in such systems, we studied the dust ring with crescent around the VLM star ZZ~Tau~IRS using the Karl G. Jansky Very Large Array (JVLA) at centimeter wavelengths. Significant signals were detected around ZZ~Tau~IRS. To estimate the maximum grain size ($a_{\rm max}$) in the crescent, we compared the observed spectral energy distribution (SED) with SEDs for various $a_{\rm max}$ values predicted by radiative transfer calculations. We found $a_{\rm max} \gtrsim$~1~mm and $\lesssim$~60~$\mu$m in the crescent and ring, respectively, though our modeling efforts rely on uncertain dust properties. Our results suggest that grain growth occurred in the ZZ~Tau~IRS disk, relative to sub-micron-sized interstellar medium. Planet formation in crescent with mm-sized pebbles might proceed more efficiently than in other regions with sub-millimeter-sized pebbles via pebble accretion scenarios.