Searching for Habitable Worlds

MIT astronomers have discovered a planet some 140 light-years from Earth that is rapidly crumbling to pieces. The disintegrating world is about the mass of Mercury, although it circles about 20 times closer to its star than Mercury does to the sun, completing an orbit every 30.5 hours. At such close proximity to its star, the planet is likely covered in magma that is boiling off into space. As the roasting planet whizzes around its star, it is shedding an enormous amount of surface minerals and effectively evaporating away. Using the NASA’s Transiting Exoplanet Survey Satellite (TESS), it appears that the planet is disintegrating at a dramatic rate, shedding an amount of material equivalent to one Mount Everest each time it orbits its star. At this pace, given its small mass, the researchers predict that the planet may completely disintegrate in about 1 million to 2 million years.

"TOI-270 is a true Disneyland for exoplanet science, and one of the prime systems TESS was set out to discover," MIT Kavli Institute for Astrophysics and Space Research postdoctoral scholar Maximilian Günther said. "It is an exceptional laboratory for not one, but many reasons -- it really ticks all the boxes."

NASA’s Transiting Exoplanet Survey Satellite, TESS, has discovered its first Earth-sized exoplanet. The planet, named HD 21749c, is the smallest world outside our solar system that TESS has identified yet. ... “For stars that are very close by and very bright, we expected to find up to a couple dozen Earth-sized planets,” says lead author and TESS member Diana Dragomir, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research. “And here we are — this would be our first one, and it’s a milestone for TESS. It sets the path for finding smaller planets around even smaller stars, and those planets may potentially be habitable.”

Scientists used observations from NASA's Spitzer Space Telescope and the ground-based TRAPPIST (TRAnsiting Planets and PlanetesImals Small Telescope) telescope, as well as other ground-based observatories, to identify seven planets orbiting an ultra-cool dwarf star. All seven planets are Earth-sized and terrestrial — and all could potentially harbor liquid water.