Protoplanetary Disk Chemistry

TL;DR

This review discusses the chemistry of protoplanetary disks, highlighting how chemical compositions influence planet formation, the methods used to study these processes, and the complex links between disk chemistry, structure, and evolution.

Contribution

It synthesizes current knowledge on disk chemistry, emphasizing the roles of inheritance, in situ processes, and the dynamic links affecting chemical compositions and modeling challenges.

Findings

Disk chemical composition is influenced by inheritance and in situ chemistry.

Elemental ratios in disk gas and solids often differ from stellar values.

Linked chemical, physical, and dynamical processes offer probes of disk evolution.

Abstract

Planets form in disks of gas and dust around young stars. The disk molecular reservoirs and their chemical evolution affect all aspects of planet formation, from the coagulation of dust grains into pebbles, to the elemental and molecular compositions of the mature planet. Disk chemistry also enables unique probes of disk structures and dynamics, including those directly linked to ongoing planet formation. Here we review the protoplanetary disk chemistry of the volatile elements HOCNSP, the associated observational and theoretical methods, and the links between disk and planet chemical compositions. Three takeaways from this review are: (1) The disk chemical composition, including the organic reservoirs, is set by both inheritance and in situ chemistry. (2) Disk gas and solid O/C/N/H elemental ratios often deviate from stellar values due to a combination of condensation of molecular carriers, chemistry, and dynamics. (3) Chemical, physical, and dynamical processes in disks are closely linked, which complicates disk chemistry modeling, but these links also present an opportunity to develop chemical probes of different aspects of disk evolution and planet formation.