Hydrocarbon chemistry in inner regions of planet forming disks

Abstract

The analysis of the mid-infrared spectra helps understanding the composition of the gas in the inner, dense and warm terrestrial planet forming region of disks around young stars. ALMA has detected hydrocarbons in the outer regions of the planet forming disk and Spitzer detected \ce{C2H2} in the inner regions. JWST- MIRI provides high spectral resolution observations of \ce{C2H2} and a suite of more complex hydrocarbons are now reported. Interpreting the fluxes observed in the spectra is challenging and radiation thermo-chemical codes are needed to properly take into account the disk structure, radiative transfer, chemistry and thermal balance. Various disk physical parameters like the gas-to-dust ratio, dust evolution including radial drift, dust growth and settling can affect the fluxes observed in the mid-IR. Still, thermo-chemical disk models were not always successful in matching all observed molecular emission bands simultaneously. The goal of this project is two-fold. We analyse the warm carbon chemistry in the inner regions of the disk, i.e. within 10 au to find pathways forming \ce{C2H2} potentially missing from the existing chemical networks. Second, we analyse the effect of the new chemistry on the line fluxes of acetylene. We use radiative thermo-chemical disk code {P{\small RO}D{\small I}M{\small O}} to expand the hydrocarbon chemistry that occurs in a typical standard T Tauri disks. We used the UMIST and the KIDA rate databases for collecting reactions for the species. We include a number of three-body and thermal decomposition reactions from STAND2020 network. We included isotopomers for the species that were present in the databases. The chemistry is then analysed in the regions that produce observable features in the mid-infrared spectra. The effect of expanding the hydrocarbon chemistry on the mid-infrared spectra is studied. Acetylene is formed via two ....

arXiv commentaccepted for publication in A&A

References in corpus (31)

• The UMIST database for astrochemistry 2012
• Structure of Stationary Photodissociation Fronts
• A KInetic Database for Astrochemistry (KIDA)
• Photodissociation and photoionisation of atoms and molecules of astrophysical interest
• The 2014 KIDA network for interstellar chemistry
• Radiation thermo-chemical models of protoplanetary disks I. Hydrostatic disk structure and inner rim
• Titan's Atmosphere and Climate
• Consistent dust and gas models for protoplanetary disks. I. Disk shape, dust settling, opacities, and PAHs
• H2O and OH gas in the terrestrial planet-forming zones of protoplanetary disks
• A Spitzer survey of mid-infrared molecular emission from protoplanetary disks I: Detection rates
• The molecular composition of the planet-forming regions of protoplanetary disks across the luminosity regime
• Hydrocarbon emission rings in protoplanetary disks induced by dust evolution
• Organic Molecules and Water in the Inner Disks of T Tauri Stars
• A Chemical Kinetics Network for Lightning and Life in Planetary Atmospheres
• Radiation thermo-chemical models of protoplanetary disks II. Line diagnostics
• Formation of simple organic molecules in inner T Tauri disks
• Consistent dust and gas models for protoplanetary disks: II. Chemical networks and rates
• First detection of c-C3H2 in a circumstellar disk
• Molecules with ALMA at Planet-forming Scales (MAPS) VI: Distribution of the small organics HCN, C2H, and H2CO
• Molecules with ALMA at Planet-forming Scales (MAPS). IX. Distribution and Properties of the Large Organic Molecules HC${}_3$N, CH${}_3$CN, and $c$-C${}_3$H${}_2$
• Modelling mid-infrared molecular emission lines from T Tauri stars
• FUV and X-ray irradiated protoplanetary disks: a grid of models I. The disk structure
• The chemistry of cosmic dust analogues from C, C${}_2$, and C${}_2$H${}_2$ in C-rich circumstellar envelopes
• Observing Carbon & Oxygen Carriers in Protoplanetary Disks at Mid-infrared Wavelengths
• Benzene formation in the inner regions of protostellar disks
• Exploring organic chemistry in planet-forming zones
• X-ray radiative transfer in protoplanetary disks - The role of dust and X-ray background fields
• The effects of dust evolution on disks in the mid-IR
• The connection between warm carbon chain chemistry and interstellar irradiation of star-forming cores
• The infrared line-emitting regions of T Tauri protoplanetary disks
• Water shielding in the terrestrial planet-forming zone: Implication for inner disk organics

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