Science with an ngVLA: High-resolution imaging of comets

TL;DR

The paper discusses how the ngVLA radio interferometer can revolutionize cometary science by enabling high-resolution mapping of gases, molecules, and dust in comets, providing insights into their composition and activity.

Contribution

It introduces the capabilities of the ngVLA for detailed comet observations, including detection of key molecules and imaging of the nucleus and dust grains, which were not possible before.

Findings

Enables detection and mapping of key coma species in 1.2-116 GHz range.

Allows high-resolution imaging of fundamental molecules like OH and NH3.

Potential to image thermal emission from comet nuclei and dust grains.

Abstract

Detailed mapping of the distributions and kinematics of gases in cometary comae at radio wavelengths can provide fundamental advances in our understanding of cometary activity and outgassing mechanisms. Furthermore, the measurement of molecular abundances in comets provides new insights into the chemical composition of some of the Solar System's oldest and most primitive materials. Here we investigate the opportunities for significant progress in cometary science using a very large radio interferometer. The ngVLA concept will enable detection and mapping of a range of key coma species in the 1.2-116 GHz range, and will allow for the first time, high-resolution mapping of the fundamental cometary molecules OH and NH$_3$. The extremely high angular resolution and continuum sensitivity of the proposed ngVLA will also allow the possibility of imaging thermal emission from the nucleus itself, as well as large dust/ice grains in the comae, of comets passing within $\sim1$ au of Earth.