NASA’s Transiting Exoplanet Survey Satellite (TESS) has discovered several new exoplanets — planets orbiting stars outside our solar system — located just 31 light-years away from Earth. They are orbiting an M-dwarf star, called GJ 357 in the Hydra constellation. The star is 40% cooler than our sun and 1/3 of its mass as well as size. The first exoplanet discovered orbiting around the star was GJ 357 b.
GJ 357 b is 22% larger and 80% larger than Earth, making it officially a Super-Earth. Unfortunately, it has an average temperature of 490° Fahrenheit and completes one orbit around the star every 3.9 days. Other exoplanets discovered include GJ 357 d, which is a Super-Earth that is 6.1 times the Earth’s mass, and orbits the star at a distance where the temperature might be perfect to support liquid water on the surface. It’s not known if it is rocky like our Earth, but it orbits the star every 55.7 days and has a temperature of -64° Fahrenheit. However, an atmosphere could cause it to be warmer. Right smack in the middle of those two planets is GJ 357 c, which is 3.4 times the mass of Earth and orbits the star every 9.1 days, reaching a temperature of 260° Fahrenheit.
“We describe GJ 357 b as a ‘hot Earth,’. Although it cannot host life, it is noteworthy as the third-nearest transiting exoplanet known to date and one of the best rocky planets we have for measuring the composition of any atmosphere it may possess,” said Enric Pallé, study co-author and astrophysicist at the Institute of Astrophysics of the Canary Islands.