Medium-Resolution Spectrometer Archives

Top: coma maps of H2O, CO2, and CH4, computed as the molecular column density from a pixel-by-pixel retrieval analysis for Observations 6, 15, and 6, respectively. The sunward and target velocity directions are denoted by the white arrows. The target centroids, computed as the photocenter in the median-stacked images (Figure 1), are marked with the black points. For H2O and CO2, the white contours correspond to emission levels of 50% and 20% relative to the maximum value and illustrate the slight antisunward extension of the respective comae. The contours are omitted in the CH4 panel, due to the poorer signal-to-noise ratio of the data. Bottom: corresponding median-stacked images across the continuum wavelengths within each fluorescence region. The H2O coma map shows a significant enhancement in the emission level at large nucleocentric distances relative to the dust continuum, indicating extended H2O production within the coma. -- The Astrophysical Journal Letters

Astrochemistry, Astronomy & Telescopes, Biogeochemical Cycles & Geobiology, Biophysics, Biosignatures & Paleobiology, Comets and Asteroids, Icy Worlds, Imaging & Spectroscopy, Interstellar, Press Release

Webb Detects Methane on Interstellar Comet 3I/ATLAS

by Keith CowingJune 2, 2026June 2, 2026

NASA’s James Webb Space Telescope has collected its first mid-infrared chemical fingerprint of an interstellar object during a recent revisit to comet 3I/ATLAS. The team’s results published recently in The […]

Top: MIRI-MRS spectra of VHS 1256 b, with the spectral regions used for molecular detection highlighted for each species. Bottom: Corresponding Exo-REM molecular templates for the detected molecules, showing both the highlighted bands and the specific spectral features that were identified in the observations through cross-correlation. -- astro-ph.EP

Astrochemistry, Astronomy & Telescopes, Atmospheres, Climate, Weather, Biochemistry & Organic Chemistry, Biophysics, Biosignatures & Paleobiology, Exoplanets, -moons, -comets, Imaging & Spectroscopy, Status Report

The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. VIII. Molecular Mapping Performance With JWST/MIRI MRS: VHS 1256 b As A Case Study

by Keith CowingMarch 18, 2026March 18, 2026

VHS 1256 b was the first planetary-mass companion to be observed with the James Webb Space Telescope’s Mid-Infrared Instrument (JWST/MIRI) using the Medium-Resolution Spectrometer (MRS).