Helium escaping from the atmosphere of a nearby rocky exoplanet orbiting in a habitable zone

arXiv:2607.14326 · astro-ph.EP · Submitted 2026-07-15 · Read on arXiv

Collin Cherubim, Shreyas Vissapragada, Tim Cunningham, Annabella G. Meech, David Charbonneau, Robin Wordsworth, Aaron Householder, Johanna Teske, Leonardo A. Dos Santos, Nicole L. Wallack, William Misener, Zifan Lin, Andrew McWilliam, Michael Zhang, Jason A. Dittmann, Mercedes López-Morales

astro-ph.EP

Submitted: 2026-07-15

Comments: Published in Science on July 16, 2026

DOI: 10.1126/science.aea9708

License: http://creativecommons.org/licenses/by/4.0/

The gist: Observations of highly irradiated gas giant exoplanets have shown helium escaping from their atmospheres.

Terminology

Aperture — 11× in this paper · explained in 1 episode
Abundance — 6× in this paper · explained in 1 episode
Core — 5× in this paper · explained in 2 episodes
European Photon Imaging Camera — 3× in this paper
Transmission spectroscopy — 3× in this paper · explained in 2 episodes
Calibration — 2× in this paper · explained in 7 episodes
Trace — 2× in this paper · explained in 2 episodes
AGN — 1× in this paper · explained in 1 episode
Bayesian Inference — 1× in this paper · explained in 5 episodes
HITRAN Application Programming Interface — 1× in this paper
Initial Data — 1× in this paper · explained in 2 episodes
Markov Chain Monte Carlo — 1× in this paper
Metal Oxide Semi-conductor — 1× in this paper
Signal-to-noise ratio (SNR) — 1× in this paper · explained in 2 episodes
Society of Photo-Optical Instrumentation Engineers — 1× in this paper
Universal Time — 1× in this paper

Abstract

Observations of highly irradiated gas giant exoplanets have shown helium escaping from their atmospheres. There is limited evidence for atmospheres on rocky exoplanets, perhaps because they have already escaped. We report spectroscopic observations of LHS 1140b, a rocky exoplanet that orbits in the habitable zone of a nearby low-mass star. The near-infrared transit spectra show absorption by helium escaping from the planet's atmosphere. Helium absorption is detected in 2024 but not in 2025, indicating time-variable atmospheric escape. We interpret these results as indicating an upper atmosphere dominated by helium and depleted in hydrogen, with other volatile species trapped at lower altitudes, consistent with atmospheric fractionation models. No helium absorption is detected for LHS 1140c, a smaller and more heavily irradiated exoplanet in the same system.

Sources

SpectRes: A Fast Spectral Resampling Tool in Python

Terminology

Abstract

Sources

Related papers