Imaging of the CO Snow Line in a Solar Nebula Analog

TL;DR

This study uses high-resolution ALMA observations of N2H+ to image the CO snow line in the disk around TW Hya, providing insights into planet formation regions in a solar nebula analog.

Contribution

First direct chemical imaging of the CO snow line in a solar nebula analog using N2H+ as a tracer with high spatial resolution.

Findings

CO snow line located at ~30 AU in TW Hya disk

N2H+ emission forms a ring matching snow line predictions

Results inform models of Solar System formation

Abstract

Planets form in the disks around young stars. Their formation efficiency and composition are intimately linked to the protoplanetary disk locations of "snow lines" of abundant volatiles. We present chemical imaging of the CO snow line in the disk around TW Hya, an analog of the solar nebula, using high spatial and spectral resolution Atacama Large Millimeter/Submillimeter Array (ALMA) observations of N2H+, a reactive ion present in large abundance only where CO is frozen out. The N2H+ emission is distributed in a large ring, with an inner radius that matches CO snow line model predictions. The extracted CO snow line radius of ~ 30 AU helps to assess models of the formation dynamics of the Solar System, when combined with measurements of the bulk composition of planets and comets.