Webb Telescope Discovers Hidden Atmosphere on Molten Super-Earth TOI-561 b Despite Extreme Heat

Astronomers using NASA's James Webb Space Telescope have discovered the most direct evidence yet that a rocky planet orbiting a distant star has an atmosphere. The ultra-hot super-Earth TOI-561 b rushes around its star in fewer than 11 hours, all the while maintaining a substantial gaseous envelope over a global magma ocean. They reveal that while the extreme radiation of its nearby star would be expected to strip any atmosphere from the planet, observations show it is less dense than anticipated, a clue that stable reservoirs of gaseous volcanic materials exist atop its molten surface, erupting and then recondensing onto the planet in a new form.

Webb Telescope Reveals Ultra-Hot Super-Earth TOI-561 b Has Thick Atmosphere Despite Lava Surface

According to a report in The Astrophysical Journal Letters, researchers noted that TOI-561 b's radius is about 1.4 times Earth's, and it orbits extremely close to its star, less than one-fortieth the distance between Mercury and the Sun—locking one side permanently in daylight. Dr. Anjali Piette explained winds transfer heat to the nightside, while gases cool the atmosphere; Teske noted low density may result from a smaller iron core.

Webb's NIRSpec found the dayside at 1,800°C, indicating a thick atmosphere; Lichtenberg called it “a wet lava ball” balancing gases with its magma ocean.

Webb Observations Reveal TOI-561 b Defies Expectations, Retaining Atmosphere Despite Extreme Stellar Radiation

The observations come from Webb's General Observers Program 3860, which monitored the planet continuously for 37 hours over nearly four orbits. Scientists have now moved to map temperature differences across the planet and fully describe its atmospheric ingredients.

The find reignites the debate around whether such small planets can retain an atmosphere, under normal conditions, a necessity for life as we know it, under intense radiation.