Scientists Discover Strongest Evidence Yet Of An Atmosphere On A Molten Rocky Exoplanet | World News
The James Webb Space Telescope has made significant progress in detecting atmospheres around exoplanets since it began scientific operations in mid-2022. These data include providing the first clear evidence of carbon dioxide in an exoplanet’s atmosphere (WASP-39b), atmospheric water vapor (WASP-96 b), and even heavier elements such as oxygen and carbon (HD149026b).
According to the latest statement, researchers announced that the strongest evidence to date of the atmosphere around a rocky planet has been detected.
Meet TOI-561 b: A Planet of Fire and Gas
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The planet at the center of this breakthrough is TOI-561 b, an extremely hot super-Earth located about 275 light-years from Earth. The rocky world, which is approximately 1.4 times the radius of Earth, completes an orbit around a Sun-like star in less than 11 hours, placing it in the rare category of ultra-short period (USP) exoplanets.
Observations with Webb’s Near Infrared Spectrometer (NIRSpec) suggest that TOI-561 b is covered by a global magma ocean overlain by a thick layer of gas. This directly challenges the long-held assumption that small rocky planets orbiting so close to their stars would rapidly lose their atmospheres due to intense stellar radiation.
A discovery that challenges the Planet Theory
The research was led by Johanna Teske of the Earth and Planets Laboratory at the Carnegie Institution for Science and an international team of astronomers. Their findings were published December 11 in The Astrophysical Journal Letters.
Because TOI-561 b orbits less than one-fortieth of the distance between Mercury and the Sun, scientists believe the planet is tidally locked, meaning one side is constantly facing its star. As a result, dayside temperatures rise beyond the melting point of the rocks, creating a large surface covered in lava.
Surprisingly, measurements of the planet’s mass and size reveal a lower density than expected. This could be a sign of a relatively small iron core and a mantle of rocks less dense than Earth’s, or it could mean that the atmosphere is making the planet appear larger than it actually is.
Tracking Temperature to Reveal an Atmosphere
To test whether TOI-561 b actually has an atmosphere, the team observed the system for more than 37 hours as the planet completed approximately four orbits. They measured changes in brightness as the planet passed behind its star; This method was similar to, but inverse to, the transit technique commonly used to discover exoplanets.
If the planet did not have an atmosphere, it would not be able to redistribute heat, resulting in daytime temperatures around 2,700°C. Instead, Webb recorded a significantly cooler temperature of around 1,800°C.
This temperature difference strongly indicates the existence of an atmosphere that can transfer heat between the day side and night side of the planet.
The World of ‘Wet Lava Ball’
Despite the evidence, a great mystery remains: How does such a small planet, exposed to extreme radiation bombardment, manage to cling to a dense atmosphere?
The researchers suggest that TOI-561 b exists in a delicate balance between its magma ocean and atmosphere. Gases released from the molten surface feed the atmosphere, while the magma simultaneously sucks them back into the planet’s interior.
To explain the observations, scientists believe the planet must be much richer in volatile elements than Earth, leading researchers to give it a striking description as something akin to a “wet lava ball.”
What’s Next?
These findings mark the first results from General Observers Program 3860, part of Webb’s Cycle 2 mission. Scientists are now analyzing the entire data set to map temperatures on both the day and night sides of TOI-561 b and better understand the composition of its atmosphere.
If confirmed in more detail, the discovery could expand the list of worlds that could harbor atmospheres even under the most extreme cosmic conditions and reshape how astronomers think about rocky planets beyond our solar system.
