Overview
- A multi-author paper in Science synthesizes a 2024 ground-based detection of helium, 2025 non-detections, and new X-ray and age estimates to argue LHS 1140b likely keeps a layered atmosphere.
- Magellan Clay transit spectra from 2024 showed helium escaping from the planet’s upper layers, which is a sensitive sign of an atmosphere rather than a bare rock.
- X-ray measurements of the host red dwarf and the planet’s age imply the observed helium should have been lost long ago unless the planet is actively replenishing it, supporting the replenishment hypothesis.
- Researchers interpret the mixed detections as a multi-layer structure with light helium in the upper atmosphere and heavier molecules such as water or CO2 trapped at lower altitudes, though composition near the surface remains unconfirmed.
- LHS 1140b, a roughly 5.6 Earth-mass, 1.7 Earth-radius world about 40 light-years away, is now a priority target for the JWST/Hubble Rocky Worlds DDT program to confirm or refute the atmospheric claim and assess habitability implications.