JWST Maps Anisotropic Molecular Emissions in Oort Cloud Comet C/2022 E3 (ZTF)

The Milam et al. survey used JWST NIRSpec and MIRI to produce column-density and rotational-temperature maps for eight species plus continuum. Anisotropic outgassing was universal, yet H2O alone traced a different spatial pattern, implying separate active regions or sublimation physics on the nucleus. Coma-averaged OPR for water reached the statistical value of 3 and the 12CO2/13CO2 ratio matched the terrestrial 89, reinforcing inheritance from the interstellar medium rather than reprocessing.

Dust modeling of the sub-micron grains yields a crystalline mass fraction of 0.2385, intermediate between previous JWST comets and ground-based infrared surveys. This places C/2022 E3 among the moderately processed Oort-cloud population and supplies a new anchor point for comparing dynamical families. The data also supply the first JWST spatial temperature maps of CO and CH3OH, revealing thermal gradients that future thermophysical models must reproduce.

Because the observations occurred post-perihelion, they capture the comet after peak heating, when seasonal effects and possible layering become visible. Extending the same mapping strategy to a statistically meaningful sample of dynamically new versus returning comets would test whether crystalline fractions correlate with orbital history or formation distance.

The principal limitation remains single-epoch coverage at one heliocentric distance; repeated visits across a full orbit would separate transient jets from secular evolution of the nucleus.