NASA's exoplanet hunter detected one potentially habitable world that is larger than Earth and two others, whose types cannot be found in the Solar System.
The newly-discovered exoplanets orbit a nearby star called Transiting Exoplanet Survey Satellite (TESS) Object of Interest (TOI) 270.
Astronomers reported the discovery in a study published in the journal Nature Astronomy on July 29
Earth's Super Twin
Astronomers predict that the innermost planet orbiting TOI 270 b is a rocky planet that is about 25 percent larger than Earth. It has a revolution of 3.4 days and a distance to its star that is about 13 times closer than that of Mercury to the Sun.
Due to its proximity to its star, TOI 270 b is hot with temperatures reaching around 490 degrees Fahrenheit (254 degrees Celsius). Its mass is also 1.9 times than that of Earth's.
The other two exoplanets, TOI 270 c and d, are 2.4 and 2.1 times bigger than the Earth's size. They orbit the same star every 5.7 and 11.4 days respectively.
Unlike the b world, the two other planets have similar composition with Neptune's gaseous environment.
"It is uncommon for planets to have sizes between 1.5 and two times that of Earth for reasons likely related to the way planets form, but this is still a highly controversial topic," said co-author Fran Pozuelos, a postdoctoral researcher at the University of Liège in Belgium. "TOI 270 is an excellent laboratory for studying the margins of this gap and will help us better understand how planetary systems form and evolve."
A particularly interesting part of the system is the outermost planet called TOI 270 d. It has the lowest temperature of all the other worlds, which is about 150 degrees Fahrenheit (66 degrees Celsius).
Co-author Adina Feinstein, a PhD student at the University of Chicago, said TOI 270 will be observable by the James Webb Space Telescope for over half a year.
Future studies may explore additional rocky planets at farther distances, where lower temperatures could allow the formation of water on the surface.