The “most eccentric” exoplanet ever found has been detected by a team of international researchers led by the University of Bern. This exoplanet, which has been named TOI-2257 b, is a “sub-Neptune” which means that it is smaller than the furthest planet in our Solar System.
Thanks to data collected by NASA's Transiting Exoplanet Survey Satellite (TESS), a small red dwarf star was found and studied for four months. Experts were able to gather important additional data by using the SAINT-EX telescope in Mexico. TOI-2257 b was detected by the transit method which means that it was seen passing in front of its host star by causing a dip in the red dwarf’s brightness.
The researchers found that the exoplanet has a short orbital period and may possibly have water as explained by the University of Bern, “With its 35-day orbital period, TOI-2257 b orbits the host star at a distance where liquid water is possible on the planet, and therefore conditions favorable for the emergence of life could exist.” But don’t get excited yet, as there probably isn’t any life since its radius is approximately 2.2 times bigger than Earth’s which “suggests that the planet is rather gaseous, with high atmospheric pressure not conducive to life.”
Nicole Schanche from Bern University noted, “In terms of potential habitability, this is bad news,” adding, “While the planet's average temperature is comfortable, it varies from -80°C to about 100°C depending on where in its orbit the planet is, far from or close to the star.”
Another discovery they made was that the planet has a very odd orbit around its star. “We found that TOI-2257 b does not have a circular, concentric orbit,” Schanche said. It has even been described as being the “most eccentric planet” that has ever been found orbiting a cool star.
As for why it has such an unusual orbit, one possibility is that there could be a massive planet located further away from the star which is affecting the orbit of TOI-2257 b. However, that is just a theory for now as further analysis needs to be conducted in order to know for sure.
Their study was published in Astronomy & Astrophysics where it can be read in full.