Water Shielding in the Terrestrial Planet-forming Zone: Implication for Inner Disk Organics

The chemical composition of the inner region protoplanetary disks can trace planetary building material. exact elemental disk has not yet been measured and tensions between models observations still exist. Recent advancements have shown UV-shielding to be able increase emission organics. Here, we expand on these investigate how may impact in 5 au. In this work, use model from arxiv:2204.07108 it with a larger network. We focus abundances upper atmosphere where effects water are most prominent molecular lines originate. find rich carbon nitrogen chemistry enhanced C2H2, CH4, HCN, CH3CN, NH3 by > 3 orders magnitude. This is caused self-shielding H2O, which locks oxygen water. subsequently results suppression oxygen-containing species like CO CO2. C2H2 seen inclusion allows us explain observed abundance without resorting elevated C/O ratios as induced an effectively oxygen-poor environment oxygen-rich gas. Thus, important for reproducing hydrocarbons nitriles. From our result, NH3, NO expected observable James Webb Space Telescope (JWST).