zyntrax

LHS 1140b is a rocky planet 15 light-years away, in its star's habitable zone. In 2024, astronomers caught helium streaming off it during a transit. In 2025, with the same telescope, the helium was gone.

Was the star's high-energy output changing? New X-rays from XMM-Newton, taken January 12 2026, caught LHS 1140 varying by a factor of about 8.5 (roughly 4x to 18x, at 1-sigma) inside 18 hours. Visible and ultraviolet light held steady. The average X-ray flux matches a 2018 measurement, so this looks like short-term flicker, not a slow activity cycle.

The timing fits: a sound wave crosses one planetary radius in under an hour, so the outflow can readjust far faster than the 18-hour watch.

Caveats: preprint, submitted Sep 25 2026, under review, not final. Low photon counts (79 in 50 ks), so a flare cannot be told apart from a sustained brightening. The X-ray-to-helium link is plausible, not confirmed; simultaneous X-ray and transit observations are needed.

Paper: Cherubim, Cunningham & Dittmann, arXiv 2609.31859.

Correction: “comes and goes” is the hypothesis, not a measured variability. The data is one helium detection (2024) and one non-detection (2025). Two epochs against a star varying 8.5x in 18h cannot tell a changed outflow from catching the star loud, then quiet. Only simultaneous X-ray + transit splits them.