Eccentric exoplanet found in Red Dwarf habitable zone

Astronomers have found a planet in the habitable zone of a red dwarf star, but its orbit is so elongated that it would have extremely variable temperatures and likely could not support life.

The planet, named TOI-2257b, was first spotted using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) planet hunting telescope, and then observed in more detail using the telescope. world of the Las Cumbres observatory and the SAINT-EX telescope in Mexico. Using SAINT-EX observations, the researchers were able to confirm that a planet orbiting the red dwarf star every 35 days.

The SAINT-EX telescope.
The SAINT-EX telescope Institute of Astronomy, UNAM / E. Cadena

Because red dwarf stars are smaller and cooler than our sun, the habitable zone around them, or the area in which liquid water might exist on the surface of an orbiting planet, is also different. Planets orbiting red dwarf stars might have liquid water even though they orbit much closer than Earth orbit the sun. And having the planet near the star also makes it easier to spot.

However, even though TOI-2257 b is in the living area, do not plan to move there just yet. The first habitability problem is that the planet has a radius of 2.2 times that of Earth, which means that it is large and probably gaseous with high atmospheric pressure. The second most intriguing fact about this planet is that it has a very eccentric orbit, meaning that its orbit follows an elliptical or oval shape rather than a circle. Sometimes the planet is close to its star, and other times it is further away.

In fact, it has the most eccentric orbit of a planet around a cold star discovered to date. And that has a big effect on the surface temperatures there.

“We have found that TOI-2257 b does not have a circular and concentric orbit,” principal researcher Nicole Schanche explained in a declaration. “In terms of potential livability, this is bad news. While the average temperature of the planet is comfortable, it varies from -80 ° C to around 100 ° C depending on where the planet is in its orbit, far or near the star.

Researchers are curious as to why the planet’s orbit is so eccentric, which could be due to a giant planet in the same system affecting that planet’s orbit. To find out more, the researchers hope the planet can be studied further using the James Webb Space Telescope.


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