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Around a dim Red-dwarf star known as TOI-2257 located 188.5 light-years away in the constellation of Camelopardalis, an international team of researchers led by The University of Bern have discovered what they are calling a ‘sub-Neptunian’ exoplanet within the star’s habitable zone. The exciting discovery was made by combining observations from the SAINT-EX Observatory in Mexico and NASA’s Transiting Exoplanet Survey Satellite TESS space telescope.
Dr. Nicole Schanche of the Center for Space and Habitability CSH of the University of Bern, the team leader, published their report in the journal Astronomy & Astrophysics naming the planet TOI-2257 b. Dr. Schanche explained.
“Despite their cool temperatures, M-dwarf (red dwarf) stars have become hot targets for exoplanet surveys, The large planet-to-star ratios of these systems result in relatively deep transits and large radial velocity amplitudes.”
“In addition, they emit more strongly in the infrared. This leads to favorable conditions for atmospheric characterization by the NASA/ESA Hubble Space Telescope and the NASA/ESA/CSA James Webb Space Telescope.”
“While space-based discoveries have been led by NASA’s Kepler and K2 missions, TESS is making a growing contribution to the population of planet-hosting M dwarfs, with 28 of 185 such planets discovered. Of those, only 17 are transiting planets in long-period (over 15 day) orbits.”
An Alien World In The Habitable Zone
TOI-2257b is a truly alien world in every sense of the word, it is 2.2 times larger than the earth. But because the Red dwarf star is so much dimmer and smaller than a class G star like our Sun, its habitable zone, where temperatures are correct for liquid water and therefore life to theoretically exist is much closer to the star.
“The long transit duration suggests the planet is in a highly eccentric orbit (e ~ 0.5), which would make it the most eccentric planet known to be transiting an M-dwarf star,” the astronomers said.
“TOI-2257b 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,” they added.
“Planets in this so-called habitable zone near a small red dwarf star are easier to study because they have shorter orbital periods and can therefore be observed more often.”
That means that TOI-2257b orbits its sun at an incredible rate of once 35.19 days, and the orbit is not circular swinging wildly away from the star so that the temperatures vary massively.
“We found that TOI-2257b does not have a circular, concentric orbit,” Dr. Schanche said.
“A possible explanation for this surprising orbit is that further out in the system a giant planet is lurking and disturbing the orbit of TOI 2257b.”
“Further observations measuring the radial velocity of the star will help confirm the eccentricity and search for possible additional planets that could not be observed in transit.”
According to Sci-News, unfortunately, the astronomers wrote that prospects for life on the massive world are not very good.
“The radius of TOI-2257b suggests that the planet is rather gaseous, with high atmospheric pressure not conducive to life.”
“In terms of potential habitability, this is bad news: while the planet’s average temperature is comfortable, it varies from minus 80 degrees Celsius to about 100 degrees Celsius (from minus 112 to 212 degrees Fahrenheit) depending on where in its orbit the planet is, far from or close to the star.”
However, the strange perturbation of the world’s orbit merits further observation and makes it a wonderful candidate for the brand new James Webb Telescope to search for additional planets that could be influencing its orbit.
