Researchers using NASA’s James Webb Space Telescope have found strong evidence of an atmosphere around the rocky planet TOI-561 b, marking a significant breakthrough in our understanding of exoplanets. Located outside our solar system, TOI-561 b orbits very close to its star, leading to some surprising discoveries.
TOI-561 b is about 1.4 times the radius of Earth and completes an orbit in under 11 hours. Its proximity to its host star—which is slightly smaller than the Sun—means the planet is likely tidally locked. This results in extreme temperatures, making the daytime side much hotter than typical rock can handle.
Johanna Teske, a leading scientist in this study from Carnegie Science, noted an unusual characteristic of TOI-561 b: its unexpectedly low density. “It’s not a super-puff, but it is less dense than you would expect for a planet made of Earth-like materials,” she said. This raises intriguing questions about its composition.
One idea suggests that the planet has a small iron core and a less dense rocky mantle, possibly due to its formation near an old, iron-poor star. This environment may have allowed it to accumulate a different mix of elements compared to the planets in our solar system.
Importantly, the Webb telescope’s observations suggest that TOI-561 b might be shrouded in a thick atmosphere. This atmosphere could be maintaining a more moderate temperature than expected, despite the intense radiation it receives. While smaller planets near their stars are often thought to lack atmospheres, some evidence is starting to emerge that contradicts this belief.
To investigate, researchers analyzed the planet’s temperature using Webb’s NIRSpec. They discovered that the dayside temperature of TOI-561 b is around 3,200 degrees Fahrenheit (1,800 degrees Celsius), significantly cooler than the extreme 4,900 F (2,700 C) expected for a bare rock. This discrepancy hints at heat being distributed by an atmosphere.
Anjali Piette, a contributor from the University of Birmingham, emphasized the importance of a thick, volatile-rich atmosphere. Such an atmosphere could create winds that circulate heat to the nightside and trap warmth, preventing the surface from becoming solidified entirely. This indicates a dynamic interaction between the magma ocean beneath and the atmosphere above.
While the idea of an atmosphere around such an extreme planet raises questions, experts believe it points to a balance—gases that escape into space may also be replenished by outgassing from the magma ocean. Tim Lichtenberg from the University of Groningen explains, “This planet must be much, much more volatile-rich than Earth.”
The Webb telescope has been collecting data for over 37 hours continuously as TOI-561 b orbits its star. Researchers are now analyzing this data to learn more about the planet’s atmosphere and temperature distribution.
This discovery could shift our understanding of how planets form and retain atmospheres, especially in extreme conditions. As Johanna Teske noted, “What’s exciting is that this new data opens up more questions than it answers.”
The James Webb Space Telescope continues to be a groundbreaking tool in our quest to understand the cosmos. It is designed to unravel mysteries not just in our solar system but also in distant realms beyond. Whether this fascinating find will change our perception of exoplanets remains an exciting prospect.
For more insights, explore the NASA page dedicated to the James Webb Space Telescope.
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Astrophysics, Exoplanet Atmosphere, Exoplanets, Goddard Space Flight Center, James Webb Space Telescope (JWST), Planetary Environments & Atmospheres, Science & Research, The Universe
