MINDS. JWST-MIRI reveals a peculiar CO${}_2$-rich chemistry in the drift-dominated disk CX Tau

Abstract

Radial drift of icy pebbles can have a large impact on the chemistry of the inner regions of protoplanetary disks. Compact dust disks ($\lesssim$50 au) are suggested to have a higher (cold) H${}_2$O flux than more extended disks, likely due to efficient radial drift bringing H${}_2$O-rich material to the inner disk, where it can be observed with JWST. We present JWST MIRI/MRS observations of the disk CX Tau taken as a part of the Mid-INfrared Disk Survey (MINDS) GTO program, a prime example of a drift-dominated disk. This compact disk seems peculiar: the source possesses a bright CO${}_2$ feature instead of the bright H${}_2$O expected based on its efficient radial drift. We aim to provide an explanation for this finding. We detect molecular emission from H${}_2$O, ${}^{12}$CO${}_2$, ${}^{13}$CO${}_2$, C${}_2$H${}_2$, HCN, and OH in this disk, and even demonstrate a potential detection of CO${}^{18}$O. Analysis of the ${}^{12}$CO${}_2$ and ${}^{13}$CO${}_2$ emission shows the former to be tracing a temperature of $\sim$450 K, whereas the ${}^{13}$CO${}_2$ traces a significantly colder temperature ($\sim$200 K). H${}_2$O is also securely detected both at shorter and longer wavelengths, tracing a similar temperature of $\sim$500-600 K as the CO${}_2$ emission. We also find evidence for a colder, $\sim$200 K H${}_2$O component at longer wavelengths, which is in line with this disk having strong radial drift. The cold ${}^{13}$CO${}_2$ and H${}_2$O emission indicate that radial drift of ices likely plays an important role in setting the chemistry of the inner disk of CX Tau. Potentially, the H${}_2$O-rich gas has already advected onto the central star, which is now followed by an enhancement of comparatively CO${}_2$-rich gas reaching the inner disk, explaining the enhancement of CO${}_2$ emission in CX Tau. The comparatively weaker H${}_2$O emission can be explained by the source's low accretion luminosity. (abridged)

23 pages, 17 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (41)

• An Optical Spectroscopic Study of T Tauri Stars. I. Photospheric Properties
• UV excess measures of accretion onto young very low-mass stars and brown dwarfs
• The stickiness of micrometer-sized water-ice particles
• Astrochemistry and compositions of planetary systems
• H2O and OH gas in the terrestrial planet-forming zones of protoplanetary disks
• Chemical enrichment of giant planets and discs due to pebble drift
• JWST MIRI flight performance: The Medium-Resolution Spectrometer
• Demographics of Transition Objects
• VIP: Vortex Image Processing package for high-contrast direct imaging
• Contacts of Water Ice in Protoplanetary Disks - Laboratory Experiments
• Different dust and gas radial extents in protoplanetary disks: consistent models of grain growth and CO emission
• CO Depletion in Protoplanetary Disks: A Unified Picture Combining Physical Sequestration and Chemical Processing
• Neon Fine-Structure Line Emission By X-ray Irradiated Protoplanetary Disks
• MINDS. The detection of ${}^{13}$CO${}_2$ with JWST-MIRI indicates abundant CO${}_2$ in a protoplanetary disk
• Hints for icy pebble migration feeding an oxygen-rich chemistry in the inner planet-forming region of disks
• Probing stellar accretion with mid-infrared hydrogen lines
• High gas/dust size ratio indicating efficient radial drift in the mm-faint CX Tau disk
• Abundant hydrocarbons in the disk around a very-low-mass star
• MINDS. Abundant water and varying C/O across the disk of Sz 98 as seen by JWST/MIRI
• Dynamical Masses of Low Mass Stars in the Taurus and Ophiuchus Star Forming Regions
• Atomic Diagnostics of X-ray Irradiated Protoplanetary Disks
• Protoplanetary Disk Masses from Radiative Transfer Modeling: A Case Study in Taurus
• OH mid-infrared emission as a diagnostic of H${}_2$O UV photodissociation. I. Model and application to the HH 211 shock
• Close-in ice lines and the super-stellar C/O ratio in discs around very low-mass stars
• The diverse chemistry of protoplanetary disks as revealed by JWST
• The Chemical Inventory of the Inner Regions of Planet-forming Disks -- The JWST/MINDS Program
• Carbon depletion observed inside T Tauri inner rims: Formation of icy, kilometer size planetesimals by 1 Myr
• JWST/MIRI Spectroscopy of the Disk of the Young Eruptive Star EX Lup in Quiescence
• The kinematics and excitation of infrared water vapor emission from planet-forming disks: results from spectrally-resolved surveys and guidelines for JWST spectra
• MINDS. Hydrocarbons detected by JWST/MIRI in the inner disk of Sz28 consistent with a high C/O gas-phase chemistry
• A blue depression in the optical spectra of M dwarfs
• Mind the gap: Distinguishing disc substructures and their impact on the inner disc composition
• Constraining the radial drift of millimeter-sized grains in the protoplanetary disks in Lupus
• Bayesian Analysis of Molecular Emission and Dust Continuum of Protoplanetary Disks
• Enriching inner discs and giant planets with heavy elements
• MINDS. A multi-instrument investigation into the molecule-rich JWST-MIRI spectrum of the DF Tau binary system
• OH mid-infrared emission as a diagnostic of H${}_2$O UV photodissociation. III. Application to planet-forming disks
• Water UV-shielding in the terrestrial planet-forming zone: Implications for carbon dioxide emission
• The infrared line-emitting regions of T Tauri protoplanetary disks
• Changing disc compositions via internal photoevaporation I: Solar-mass stars
• A potential site for wide-orbit giant planet formation in the IM Lup disk

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• Locked In Ice: how Pebble Drift and Volatile Entrapment can Significantly Impact Carbon and Oxygen Ratios in Evolving Protoplanetary Discs
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• XUE. JWST spectroscopy of externally irradiated disks around young intermediate-mass stars
• MINDS. Young binary systems with JWST/MIRI: Variable water-rich primaries and extended emission
• Improving Accretion Diagnostics for Young Stellar Objects with Mid-infrared Hydrogen lines from JWST/MIRI
• Molecular Similarity and Water Diversity in Coeval Binary Disks: JWST/MIRI Observations of Sz 65 and Sz 66