![Upper Panels. Maps of N × ρ for ortho-H2O and para-H2O, the derived OPR, and Trot(H2O) for the 6 µm band measured on February 28. Note that N for each species has been corrected for the derived OPR. Lower Panels. As in the upper panels for the 2.6 µm H2O bands measured on March 1. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/08/JWST-Spatial.png?fit=1200%2C683&ssl=1)
[astro-ph.EP] We report a survey of molecular emission from cometary volatiles using the James Webb Space Telescope (JWST) toward Oort cloud comet C/2022 E3 (ZTF) carried out on UT 2023 February 28 and March 1 at a heliocentric distance (rH) of 1.33 au.
These measurements of H2O, HCN, CH3OH, C2H6, CH4, CO, CO2, 13CO2, and OCS sampled post-perihelion molecular chemistry in C/2022 E3. A suite of near to mid-infrared OH (prompt emission) transitions were also detected.
This work presents nucleus-centered spectra for all detected species, spatial-spectral maps of column density and rotational temperature as a function of distance from the nucleus for all except C2H6, HCN, and OH, and maps of co-measured continuum. The spatial distributions of both quantities were anisotropic for all mapped molecules; however, H2O showed distributions distinct from the remaining species.
Coma-averaged values of the ortho-to-para ratio (OPR) for H2O and the 12CO2/13CO2 ratio derived from these maps were consistent with the statistical equilibrium value of 3 and the terrestrial value of 89, respectively.
The modeled mass fraction of the sub-micron dust grains is dominated by amorphous carbon (56%) followed by amorphous Mg:Fe pyroxene (28%), crystalline olivine (10%), and amorphous Mg:Fe olivine (5%) with a crystalline mass fraction of 0.2385(0.0008). We compare the volatile and dust composition of C/2022 E3 (ZTF) against comets measured to date, including those surveyed by JWST.
Stefanie N. Milam, Nathan X. Roth, Geronimo L. Villanueva, Dominique Bockelee-Morvan, Jacques Crovisier, David E. Harker, Michael S.P. Kelley, Kiernan D. Foster, Ian Wong, Davide Farnocchia, Marco Micheli, Heidi B. Hammel
Comments: 20 pages, 15 figures, 4 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2608.20544 [astro-ph.EP] (or arXiv:2608.20544v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2608.20544
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Submission history
From: Stefanie Milam
[v1] Thu, 20 Aug 2026 20:10:54 UTC (2,192 KB)
https://arxiv.org/abs/2608.20544
Astrobiology, astrochemistry,
