NASA's TESS Discovers 'Super-Earth' and Two Other Exoplanets Just 73 Light Years Away - Newsweek

A "super-Earth" and two other exoplanets have been discovered by NASA's Transiting Exoplanet Survey Satellite (TESS) orbiting a star that's located just 73 light years from our planet.

The three planets are among the smallest and closest exoplanets found to date, according to a team of astronomers led by Maximilian Günther, from MIT's Kavli Institute for Astrophysics and Space Research.

The star system, dubbed TOI-270 by the team, is intriguing for several reasons. For starters, unlike our own solar system, the three planets are not too dissimilar from each other when it comes to size, according to a study describing the findings, published in the journal Nature Astronomy.

The rocky super-Earth is described as such because it has a mass higher than Earth's but significantly lower than that of Uranus and Neptune. Meanwhile, the other two planets are described as "sub-Neptunes" because they are intermediate in size—around half that of the ice giant in our own solar system.

To find two of these intermediate size planets together is significant for astronomers because worlds like this provide the "missing link" when it comes to understanding planetary formation. In fact, no intermediate-sized planets exist in our solar system.

Furthermore, the three planets line up in what's known as a "resonant chain," which means the ratio of their orbits are close to whole numbers.

"For TOI-270, these planets line up like pearls on a string," Günther said in a statement. "That's a very interesting thing, because it lets us study their dynamical behavior. And you can almost expect, if there are more planets, the next one would be somewhere further out, at another integer ratio."

The researchers say that the planet furthest away also lies in the so-called "temperate zone" which mean that the upper portions of its atmosphere may be at just the right temperature to support some forms of life. The surface itself is likely far too hot to support life, due to the extremely thick atmosphere which traps heat.

Finally, TOI-270 is an excellent candidate for further study, according to the astronomers because of its proximity to Earth—meaning it is bright—and the fact that it is unusually quiet. This steady brightness provides astronomers with a good opportunity to make observations of the surrounding planets.

"There are a lot of little pieces of the puzzle that we can solve with this system," Günther said in the statement. "You can really do all the things you want to do in exoplanet science, with this system."

"TOI-270 is a true Disneyland for exoplanet science, and one of the prime systems TESS was set up to discover," he said. "It is an exceptional laboratory for not one, but many reasons—it really ticks all the boxes."

The star system will now be a target for future observations with the next-generation James Webb Telescope, which will have the power to reveal intricate details about the properties of the planets, as well as search for any additional worlds orbiting the star that may currently be undetected.