William Misener

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.

Deep inside a sub-Neptune, where pressures reach a hundred thousand bars and temperatures hit four thousand degrees, rock behaves like boiling soup. Heavy vapors of silicon and magnesium rise, cool, and fall back as a rain of solid particles.

A balloon someone forgot to tie off deflates before your eyes. That is roughly how GJ 3090b behaves: its hydrogen-helium envelope is leaking into space at a rate that surprised astronomers. The planet is only twice the size of Earth, yet it is shedding gas as if it wanted to get rid of everything superfluous as fast as possible.