Scorching Exoplanet TOI-561 b Stuns Scientists with Unexpected Atmosphere
Scorching Exoplanet TOI-561 b Stuns Scientists with Unexpected Atmosphere
Scorching Exoplanet TOI-561 b Stuns Scientists with Unexpected Atmosphere
Astronomy: Surprising Evidence of an Atmosphere on a Scorching-Hot Rocky Planet
The most compelling evidence yet of a dense atmosphere around a rocky planet outside our solar system has been found in an unexpected place.
December 12, 2025, 09:15 AM UTC
A research team has uncovered the strongest evidence to date of an atmosphere surrounding a rocky exoplanet—one that defies expectations. Led by Johanna Teske of the Carnegie Institution for Science, the group detected signs of a thick gaseous envelope around TOI-561 b, an ultrahot world thought to be blanketed in a magma ocean. Scientists had long assumed the planet was too small and too close to its star to retain an atmosphere, but observations from the James Webb Space Telescope suggest otherwise. Without one, researchers struggle to explain why the planet is nearly 1,000 degrees Celsius cooler than predicted for its orbit.
TOI-561 b completes a full orbit around its star every 10.5 Earth hours, circling at just one-fortieth the distance between Mercury and the Sun. Tidally locked, it always presents the same face to its star, which should heat that side to a searing 2,700°C if the planet were a bare rock. Yet measurements from Webb's Near-Infrared Spectrograph (NIRSpec) recorded temperatures of around 1,800°C—still extreme, but significantly lower. The team concludes that only a dense atmosphere could redistribute heat so effectively, carrying it from the scorching dayside to the planet's eternal night.
The next major question is how this exoplanet managed to hold onto its atmosphere in such a hostile environment. The intense stellar radiation should have stripped it away long ago. "Figuring this out will be incredibly exciting," Teske says. The team is now analyzing data from 37 hours of observations to map temperatures across the planet and refine their understanding of its atmospheric composition. Their findings are detailed in a forthcoming paper in The Astrophysical Journal Letters.