Revolutionary Discovery: Ancient Super Earth Has Atmosphere

Astronomers Unveil Groundbreaking Findings on TOI-561 b A **team of astronomers** from Carnegie Institution has made a groundbreaking discovery using **NASA’s James Webb Space Telescope (JWST)**. They have identified the **first clear evidence** of an atmosphere surrounding **TOI-561 b**, an ancient super Earth positioned outside our Solar System. This remarkable finding, reported in **The Astrophysical Journal Letters**, challenges existing theories about the atmospheric retention of rocky planets in extreme conditions.

TOI-561 b is about twice the mass of Earth but differs significantly in its other characteristics. This super Earth orbits perilously close to its star, at a distance roughly one-fortieth of Mercury's orbit around the Sun. Despite its star being slightly cooler and smaller than our Sun, TOI-561 b completes an orbit in just 10.56 hours, leading to one hemisphere being perpetually exposed to sunlight.

Breaking Conventional Wisdom on Planetary Atmospheres Nicole Wallack, a **postdoctoral fellow** at Carnegie and the second author of the study, explained the implications of their findings: "Historically, we would assume that such a small and hot planet would not be able to maintain an atmosphere for an extended period. However, our observations indicate that TOI-561 b is enveloped in a surprisingly thick layer of gas, contradicting our understanding of ultra-short-period planets."

In our Solar System, smaller, intensely heated planets typically lose their original gas envelopes early in their formation. However, TOI-561 b orbits a significantly older star than our Sun, which raises questions about its ability to retain an atmosphere under harsh conditions.

Unraveling the Mystery of Low Density Another intriguing aspect of this discovery relates to the planet’s surprisingly **low density**. Johanna Teske, the lead author and astronomer at Carnegie, noted, "While TOI-561 b isn’t classified as a super-puff planet, its density is lower than expected for an Earth-like structure."

Prior to their analysis, the research team considered various structural factors that could explain the planet's low density. One hypothesis proposed that TOI-561 b might possess a smaller iron core and a mantle composed of lighter rock compared to Earth. Teske elaborated on the planet's unique origins, stating, "What makes TOI-561 b stand out among ultra-short-period planets is its orbit around a very old, iron-poor star in the Milky Way's thick disk. This suggests it formed under a significantly different chemical environment than planets in our Solar System."

Insights from JWST Temperature Measurements To further investigate the planet's atmospheric conditions, the research team employed the **Near-Infrared Spectrograph (NIRSpec)** aboard the JWST to measure the temperature of TOI-561 b’s dayside. By observing the brightness of the planet in near-infrared light, the researchers could track how the light changes as the planet passes behind its star.

If TOI-561 b lacked an atmosphere, scientists expected the temperature on its dayside to soar to nearly 4,900 degrees Fahrenheit (2,700 degrees Celsius). However, the measurements revealed a significantly lower temperature of about 3,200 degrees Fahrenheit (1,800 degrees Celsius). This notable difference hints at a redistribution of heat across the planet's surface.

The Role of Wind and Atmospheric Composition In light of the cooler temperature readings, scientists considered several factors that could contribute to this phenomenon. A molten surface could facilitate some heat transfer, but without an atmosphere, the cooler nightside would likely remain solid, limiting heat movement. Another possibility is the existence of a thin layer of vaporized rock, although this alone wouldn’t suffice for adequate cooling.

Anjuli B. S. J. Choudhury, a co-author of the study, emphasized the need for a thicker, volatile-rich atmosphere to account for all observations.

Why This Discovery Matters The discovery of an atmosphere around TOI-561 b not only reshapes our understanding of rocky planets in extreme environments but also raises profound questions about the formation and evolution of planetary systems. The findings challenge long-held beliefs regarding what types of planets can maintain atmospheres, particularly those located close to their stars.

As astronomers continue to study TOI-561 b, they may gain insights into the conditions conducive to atmospheric retention on super Earths and other rocky planets. This knowledge could ultimately help inform the search for exoplanets that may harbor life.

What’s Next? Looking ahead, researchers will likely focus on further investigations of TOI-561 b to unravel more about its composition and atmosphere. Given its unique characteristics, this super Earth could serve as a key case study in understanding planetary atmospheres across the universe. With ongoing advancements in observational technology, the potential to discover more about **exoplanets** and their conditions is vast.

In conclusion, the implications of this research extend beyond TOI-561 b. It encourages a reevaluation of the criteria used to determine the presence of atmospheres on similar planets, thereby enriching our understanding of planetary science and the diverse range of worlds that exist beyond our Solar System.