The dark and featureless surface of rocky exoplanet LHS 3844 b from JWST mid-infrared spectroscopy
arXiv:2605.00100 · doi:10.1038/s41550-026-02860-3
Abstract
JWST has opened a new era in the study of rocky exoplanets, enabling direct characterization of their surfaces with mid-infrared spectroscopy. Different types of rock have distinct spectral features that are diagnostic of the chemical composition and other physical properties like surface texture. Measurements of these features can provide valuable clues about a planet's geologic history and interior processes. Here we report a JWST 5-12 micron thermal emission spectrum for the rocky exoplanet LHS 3844 b. It is best matched by a dark, low-silica surface, such as basalt or other olivine-rich materials. The spectrum rules out fresh powder surfaces; however, space weathering can darken the powders and make them more consistent with the data. The data also disfavor trace concentrations of CO or SO gas (with 5-sigma and 3-sigma upper limits of 100 mbar and 10 microbar, respectively). Taken together, these results are well fit by an old, space-weathered surface with no evidence of accumulated volcanic gases.
Accepted for publication in Nature Astronomy on April 8, 2026. 49 pages, 18 figures, 7 tables. The arXiv version corresponds to the original submitted manuscript and will be updated with a post-acceptance version at a later time
References in corpus (30)
- Array Programming with NumPy
- The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
- The Transiting Exoplanet Survey Satellite
- The James Webb Space Telescope
- Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
- EXOFAST: A fast exoplanetary fitting suite in IDL
- The effect of red noise on planetary transit detection
- Thermal emission from the Earth-sized exoplanet TRAPPIST-1 b using JWST
- No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c
- A reflective, metal-rich atmosphere for GJ 1214b from its JWST phase curve
- Eureka!: An End-to-End Pipeline for JWST Time-Series Observations
- A secondary atmosphere on the rocky exoplanet 55 Cancri e
- A High Internal Heat Flux and Large Core in a Warm Neptune Exoplanet
- PLATON II: New Capabilities And A Comprehensive Retrieval on HD 189733b Transit and Eclipse Data
- The SPHINX M-dwarf Spectral Grid. I. Benchmarking New Model Atmospheres to Derive Fundamental M-Dwarf Properties
- The spectrum of N from 4,500 to 15,700 cm revisited with PGOPHER
- Constraining the Thickness of the Atmosphere of TRAPPIST-1 b from its JWST Secondary Eclipse Observation
- Survival of Terrestrial N2-O2 Atmospheres in Violent XUV Environments through Efficient Atomic Line Radiative Cooling
- Combined analysis of the 12.8 and 15 JWST/MIRI eclipse observations of TRAPPIST-1 b
- Sensitive Probing of Exoplanetary Oxygen via Mid Infrared Collisional Absorption
- The influence of bulk composition on long-term interior-atmosphere evolution of terrestrial exoplanets
- Spectroscopic time series performance of the Mid-Infrared Instrument on the JWST
- The Detectability of Rocky Planet Surface and Atmosphere Composition with JWST: The Case of LHS 3844b
- Super-Earths and Earth-like Exoplanets
- New chondritic bodies identified in eight oxygen-bearing white dwarfs
- The high-energy spectrum of the nearby planet-hosting inactive mid-M dwarf LHS 3844
- Hot Rocks Survey III: A deep eclipse for LHS 1140c and a new Gaussian process method to account for correlated noise in individual pixels
- Population-level Hypothesis Testing with Rocky Planet Emission Data: A Tentative Trend in the Brightness Temperatures of M-Earths
- Stellar Models Also Limit Exoplanet Atmosphere Studies in Emission
- Novel Physics of Escaping Secondary Atmospheres May Shape the Cosmic Shoreline