In 2024, the team led by David Charbonneau pointed the Magellan telescope with the WINERED spectrograph at LHS 1140. During transit, high-resolution spectroscopy caught the absorption line of metastable helium at 10833 Å. This ghostly trace is like the exhalation of a rocky exoplanet basking in the gentle light of a red dwarf.

The signal revealed a distiller atmosphere. Lightweight hydrogen almost entirely evaporated into interstellar space: its proportion relative to helium plummeted to 0.1%. Heavy helium, like the residue in a still, wrapped the planet in a scorching coat. The p-winds models computed a mass-loss rate of ~2×$10^8$ g/s (two tons per second, like two elephants flying off into the void) and an outflow gas temperature of 5160 K. Yet the planet’s equilibrium temperature is just 226 K, so water and other volatiles hide behind a cold trap near the surface, like in a thermos.

But the still operates intermittently. In 2025, the helium line vanished — the leakage pulsates like the breath of a sleeping giant, sometimes pausing, sometimes quickening in time with stellar flares. The neighboring planet LHS 1140c showed no hint of helium, confirming the 'cosmic shoreline' concept: at the boundary of gravity and radiation, some worlds retain gas envelopes, others remain bare rocks. LHS 1140b teeters right on the edge, proving that even around quiet old stars, planets aren't entirely safe.

Further monitoring with telescopes like JWST will map out the population of such 'stills' in the Galaxy. Three-dimensional magnetic models will show how X-ray gusts blow the lightest fractions out of planetary bowls. The discovery deepens our understanding of atmospheric evolution of rocky worlds and hints at how often secondary atmospheres, like the one preserving water on LHS 1140b, envelop potentially habitable planets.