Gliese 3090 b is a sub-Neptune, a type of planet larger than Earth but smaller than Neptune, orbiting its host star in a tight, short-period orbit. This planet is currently losing its atmosphere into space through a process known as photoevaporation, where intense radiation from the host star heats the upper atmosphere, causing gas to escape. Observations show the planet is in a rapid, transformative phase of its evolutionary history.
Researchers detected metastable helium in the planet's atmosphere using high-resolution spectroscopy, a technique that analyzes the light passing through the atmosphere to identify chemical signatures. By observing two transits, or instances where the planet passes in front of its star, they measured deep signals from escaping helium gas.
The findings suggest that the planet's lower atmosphere is likely obscured by aerosols, which are tiny suspended particles like fog or haze. This explains why previous measurements from other telescopes appeared muted. The data indicates that the planet has an atmospheric lifetime of only 300 million years, a relatively brief period for a planet that is approximately 1 billion years old.
Key findings
- Detection of escaping metastable helium confirms active photoevaporation on Gliese 3090 b.
- The planet is losing its atmosphere more rapidly than expected, with a remaining lifetime of about 300 million years.
- Atmospheric modeling suggests the presence of aerosols in the lower atmosphere, which hides deeper layers from view.
- The observed gas escape signal is variable, occasionally influenced by stellar flares from the host star.
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15. 9. 2026
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