Astrochemistry

MINDS. JWST-MIRI Reveals a Peculiar CO2-rich Chemistry in the Drift-dominated Disk CX Tau

By Keith Cowing
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astro-ph.EP
December 20, 2024
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MINDS. JWST-MIRI Reveals a Peculiar CO2-rich Chemistry in the Drift-dominated Disk CX Tau
A zoom-in of the 13.5-17.5 µm region of the CX Tau spectrum (black), together with all slab model fits to the molecular features. These models include C2H2 (yellow), HCN (orange), 12CO2 (green), 13CO2 (purple), H2O (blue) and OH (magenta). In light pink, we show a slab model demonstrating a potential detection of CO18O. The bottom panel shows the data in black, the combined model with and without the CO18O model in light pink and red, respectively. The red bar indicates the window in which the uncertainty was estimated. An artifact around 16.15 µm has been masked. The insets show close-ups of the regions around the 13CO2 emission feature and the (potential) CO18O feature. — astro-ph.EP

Radial drift of icy pebbles can have a large impact on the chemistry of the inner regions of protoplanetary disks. Compact dust disks (≲50 au) are suggested to have a higher (cold) H2O flux than more extended disks, likely due to efficient radial drift bringing H2O-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 CO2 feature instead of the bright H2O expected based on its efficient radial drift. We aim to provide an explanation for this finding.

We detect molecular emission from H2O, 12CO2, 13CO2, C2H2, HCN, and OH in this disk, and even demonstrate a potential detection of CO18O. Analysis of the 12CO2 and 13CO2 emission shows the former to be tracing a temperature of ∼450 K, whereas the 13CO2 traces a significantly colder temperature (∼200 K). H2O is also securely detected both at shorter and longer wavelengths, tracing a similar temperature of ∼500-600 K as the CO2 emission.

We also find evidence for a colder, ∼200 K H2O component at longer wavelengths, which is in line with this disk having strong radial drift. The cold 13CO2 and H2O 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 H2O-rich gas has already advected onto the central star, which is now followed by an enhancement of comparatively CO2-rich gas reaching the inner disk, explaining the enhancement of CO2 emission in CX Tau. The comparatively weaker H2O emission can be explained by the source’s low accretion luminosity. (abridged)

Marissa Vlasblom, Milou Temmink, Sierra L. Grant, Nicolas Kurtovic, Andrew D. Sellek, Ewine F. van Dishoeck, Manuel Güdel, Thomas Henning, Pierre-Olivier Lagage, David Barrado, Alessio Caratti o Garatti, Adrian M. Glauser, Inga Kamp, Fred Lahuis, Göran Olofsson, Aditya M. Arabhavi, Valentin Christiaens, Danny Gasman, Hyerin Jang, Maria Morales-Calderón, Giulia Perotti, Kamber Schwarz, Benoît Tabone

Comments: 23 pages, 17 figures, accepted for publication in Astronomy & Astrophysics
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2412.12715 [astro-ph.EP] (or arXiv:2412.12715v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2412.12715
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Submission history
From: Marissa Vlasblom
[v1] Tue, 17 Dec 2024 09:29:27 UTC (3,434 KB)
https://arxiv.org/abs/2412.12715
Astrobiology, Astrochemistry,

Keith Cowing

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻

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