A team of astronomers from Carnegie has made a groundbreaking discovery about a rocky planet beyond our Solar System. Using the James Webb Space Telescope (JWST), they found clear signs of an atmosphere surrounding a super Earth called TOI-561 b. This planet is unique; it’s about twice the mass of Earth but orbits extremely close to its star, completing a full orbit in just 10.56 hours. That means one side is always in daylight.
Nicole Wallack, a postdoctoral fellow at Carnegie, explained that most scientists believed planets like TOI-561 b, which are extremely hot and small, would lose their atmospheres quickly. Surprisingly, their observations showed a thick layer of gas surrounding the planet, challenging what was previously thought about ultra-short-period planets.
Typically, in our Solar System, small, hot planets lose their gas envelopes early on. However, TOI-561 b orbits an older star, and despite its fierce conditions, it seems to have maintained its atmosphere. This is particularly interesting because the planet’s density is lower than expected. Johanna Teske, another Carnegie scientist, noted that TOI-561 b isn’t a “super-puff” planet—that is, it isn’t fluffy like some other small planets—but its density suggests something unusual about its makeup.
Before delving into the JWST data, scientists considered the planet’s structure, contemplating whether it has a smaller iron core and a lighter mantle compared to Earth. Teske pointed out that TOI-561 b orbits an iron-poor star, hinting it formed in a different environment than the planets in our Solar System.
To evaluate the potential atmosphere, the team used JWST’s Near-Infrared Spectrograph (NIRSpec) to measure the planet’s temperature. They observed that instead of reaching nearly 4,900°F as expected without an atmosphere, TOI-561 b’s dayside temperature is about 3,200°F. This significant difference indicates that heat is likely being redistributed across the planet, leading scientists to explore further.
Strong winds, possibly creating a volatile-rich atmosphere, could explain the cooler temperature. Anjali Piette, a former Carnegie researcher, suggested that this atmosphere might contain water vapor that traps heat, making the planet appear cooler than it really is. Reflective silicate clouds could also help cool the atmosphere by bouncing back some of the star’s light.
Despite this exciting evidence for an atmosphere, questions remain. How does such a planet hold onto its gas when exposed to such intense radiation? While some atmosphere seems to escape into space, it appears that the balance between the planet’s hot magma and its atmosphere keeps some gas from disappearing too quickly.
Tim Lichtenberg from the University of Groningen suggested that a dynamic equilibrium exists between the magma ocean and the atmosphere. As gases escape from the planet, they are also being drawn back into the molten surface. He described it as akin to a “wet lava ball” because TOI-561 b likely has much more volatile content than Earth.
The findings from JWST raise as many questions as they answer. The study is part of a larger effort, monitored for over 37 hours, to map temperature patterns and better understand the planet’s atmospheric makeup.
This research illustrates the ongoing collaboration between various institutions and the potential of JWST to revolutionize our understanding of exoplanets. As Michael Walter, a director at Carnegie Science, mentioned, the groundbreaking data offers a glimpse into a new era of discoveries in exoplanet science.
For more on this topic, you can check out The Astrophysical Journal Letters for in-depth studies and insights regarding exoplanetary atmospheres.
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NASA; Space Exploration; Galaxies; Astrophysics; Cosmology; Mercury; Space Telescopes; Astronomy
