Carbon monoxide gas produced by a giant impact in the inner region of a young system

TL;DR

This study reports the detection of carbon monoxide gas associated with debris from a giant impact in a young planetary system, offering insights into planetary formation processes and impact compositions.

Contribution

It provides the first spectrally resolved detection of CO gas from a giant impact in a young system, linking impact debris to observable gas signatures.

Findings

Detection of CO gas ring co-orbiting with dust between 6-9 au.

Evidence supporting giant impacts as sources of both debris and gas.

Implication that planetary collisions can release observable gas, revealing planetary composition.

Abstract

Models of terrestrial planet formation predict that the final stages of planetary assembly, lasting tens of millions of years beyond the dispersal of young protoplanetary disks, are dominated by planetary collisions. It is through these giant impacts that planets like the young Earth grow to their final mass and achieve long-term stable orbital configurations. A key prediction is that these impacts produce debris. To date, the most compelling observational evidence for post-impact debris comes from the planetary system around the nearby 23 Myr-old A star HD 172555. This system shows large amounts of fine dust with an unusually steep size distribution and atypical dust composition, previously attributed to either a hypervelocity impact or a massive asteroid belt. Here, we report the spectrally resolved detection of a CO gas ring co-orbiting with dusty debris between ~6-9 au - a region analogous to the outer terrestrial planet region of our Solar System. Taken together, the dust and CO detections favor a giant impact between large, volatile-rich bodies. This suggests that planetary-scale collisions, analogous to the Moon-forming impact, can release large amounts of gas as well as debris, and that this gas is observable, providing a window into the composition of young planets.