2021/01/08 by D. E. Anderson, G. A. Blake, Geoffrey A. Blake +12 · 43 citations
Chemistry · Physics and Astronomy · #Analytical Chemistry (journal) #Astro and Planetary Science #Astrochemistry #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Carbon fibers #Chemistry #Infrared #Interstellar medium #Materials science #Molecular Spectroscopy and Structure #Oxygen #Physics #Planet #Protoplanetary disk #RADIUS #astro-ph.EP
paper · pdf · doi:10.3847/1538-4357/abd9c1
published in The Astrophysical Journal 909(1), 55 (IOP Publishing) · Accepted for publication in The Astrophysical Journal
arxiv created 2021/01/08 · openalex created_date 2021/01/18 · openalex publication_date 2021/03/01 · arxiv updated 2021/03/10 · openalex updated_date 2026/08/08
Abstract Infrared observations probe the warm gas in the inner regions of planet-forming disks around young Sun-like T Tauri stars. In these systems, H 2 O, OH, CO, CO 2 , C 2 H 2 , and HCN have been widely observed. However, the potentially abundant carbon carrier CH 4 remains largely unconstrained. The James Webb Space Telescope (JWST) will be able to characterize mid-infrared fluxes of CH 4 along with several other carriers of carbon and oxygen. In anticipation of the JWST mission, we model the physical and chemical structure of a T Tauri disk to predict the abundances and mid-infrared fluxes of observable molecules. A range of compositional scenarios are explored involving the destruction of refractory carbon materials and alterations to the total elemental (volatile and refractory) C/O ratio. Photon-driven chemistry in the inner disk surface layers largely destroys the initial carbon and oxygen carriers. This causes models with the same physical structure and C/O ratio to have similar steady-state surface compositions, regardless of the initial chemical abundances. Initial disk compositions are better preserved in the shielded inner disk midplane. The degree of similarity between the surface and midplane compositions in the inner disk will depend on the characteristics of vertical mixing at these radii. Our modeled fluxes of observable molecules respond sensitively to changes in the disk gas temperature, inner radius, and total elemental C/O ratio. As a result, mid-infrared observations of disks will be useful probes of these fundamental disk parameters, including the C/O ratio, which can be compared to values determined for planetary atmospheres.