TOI-561 b is a fascinating exoplanet that challenges what we know about hot rocky worlds. This ultra-hot super-Earth has a magma ocean underneath a thick atmosphere filled with volatile substances. Researchers from Carnegie Science recently published a study highlighting its unique features.
TOI-561 b orbits its star at just under 1.6 million kilometers (about 1 million miles). This distance is much shorter than the space between the Earth and Mercury. Being so close means one side of the planet is always lit, while the other is in constant darkness.
What’s remarkable is that TOI-561 b has retained its atmosphere for billions of years, even with intense radiation that usually strips other planets bare. Astronomer Nicole Wallack from Carnegie Science pointed out that based on current knowledge, we wouldn’t expect a planet like this to keep its atmosphere for long.
This planet is called an ultra-short period (USP) planet because it completes its orbit in less than 11 hours. It’s about twice the mass of Earth and has a larger radius. Interestingly, it orbits a star that’s over 10 billion years old—more than twice the age of our Sun. This star is low in iron but rich in elements like oxygen and magnesium, providing clues about the conditions when the universe was still young.
TOI-561 b has an oddly low density, about four times denser than water. This could mean it has a smaller iron core or that it’s composed of less dense rocks compared to Earth’s crust. Researchers used data from the James Webb Space Telescope (JWST) to analyze its characteristics. They spent 37 hours observing TOI-561 b and its system.
The data showed that TOI-561 b’s temperature is around 1,800 degrees Celsius (3,272 degrees Fahrenheit) instead of the expected 2,700 degrees Celsius (4,892 degrees Fahrenheit). This suggests that an atmosphere might be moderating the heat. It could do this by redistributing warmth from the dayside to the nightside or by absorbing heat through water vapor.
A big question remains: how does TOI-561 b keep its thick atmosphere while orbiting so closely to its star? Researchers believe that a balance exists between the atmosphere and the magma ocean. While some gases leak into space, others might be replenished from beneath the surface.
The planet’s iron content may aid in retaining that atmosphere, as it can trap volatile elements in its magma ocean. These findings indicate a unique mechanism: planets with high temperatures may actually generate their atmospheres at a rate faster than they lose them.
This groundbreaking study highlights the complexity of exoplanet atmospheres and opens doors for more research. Continuing to explore TOI-561 b will help us understand more about planetary formation and evolution.
For more insights into exoplanets, you can check resources from NASA and the James Webb Space Telescope.
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