JWST & Methane Ice: Infrared Spectra for Data Analysis

Novel infrared spectra of methane-containing ice mixtures, obtained using the ISEAge setup via Fourier Transform Infrared (FTIR) spectroscopy, are providing researchers with tools to more accurately interpret data from the James Webb Space Telescope (JWST). The findings, released Thursday, address a gap in laboratory data on the low-temperature phase of methane, particularly below 10 Kelvin.

The research, detailed in a status report posted to astro-ph.EP, focuses on binary mixtures of methane with water, carbon dioxide, methanol, and ammonia at both 6.7 K and 10 K. These temperatures are representative of conditions found in dark molecular clouds and around protostars in their early stages of development. Researchers found a 20% increase in band strength in the mixtures compared to commonly used values for pure methane at 10 K.

The team tested the applicability of their spectra by analyzing existing JWST data from the B335 region, probing the spatial distribution of methane within it. The data utilized the JWST MIRI-MRS spectrograph, focusing on apertures of 1.53” and 4.59”.

The work comes as JWST continues to reveal unexpected concentrations of organic molecules in various celestial environments. A separate investigation, published February 12, 2026, and led by the Center for Astrobiology (CAB), CSIC-INTA, utilizing modeling tools from the University of Oxford, detected benzene, methane, and the methyl radical in the ultra-luminous infrared galaxy IRAS 07251-0248. This galaxy’s core is heavily obscured by dust, but JWST’s infrared capabilities allowed researchers to peer through the material.

The significance of methane as a potential biosignature is also under review. Preliminary work suggests that an early Earth-like atmosphere rich in methane would be more readily detectable by JWST than the current oxygen-rich atmosphere. The new spectral data will be publicly available on Zenodo to aid in the fitting of JWST data.

Further experiments are being conducted to examine the phase transition of methane between phase II* and phase II, adding to the growing body of data available for interpreting JWST observations of interstellar and planetary environments.