A team of astronomers has identified what might be an atmosphere-free Earth-sized planet orbiting a cold, Jupiter-sized star, according to findings published in MIT News. Termed SPECULOOS-3b, this new rocky planet, discovered by a global effort including MIT and the University of Liège, raises possibilities for exoplanetary geology unlike any before.
Residing 55 light years from us, the planet circles its ultracool dwarf star in a mere 17 hours, completing a year in less time than a day on Earth. The close orbit enables the dwarf star, though 1,000 times dimmer and one-tenth the sun's size, to pummel the planet with radiation levels 16 times stronger than Earth receives from the sun. This scorching proximity is believed to have vaporized any atmosphere, if one existed, hinting at a surface laid bare to the cosmos. Co-author Julien de Wit, from MIT, emphasized the significance, saying, "With this world, we could basically start doing exoplanetary geology. How cool is that?" according to MIT News.
First detected as a blip in 2021, with more conclusive sightings in 2022, the existence of SPECULOOS-3b was substantiated through collective efforts from numerous observatories. The data suggests the planet is about Earth's size. Astronomers at MIT, particularly Benjamin Rackham, have contributed to understanding the star's properties. Rackham detailed, "We can say from our spectra and other observations that the star has a temperature of about 2,800 kelvins, it is about 7 billion years old — not too young, and not too old — and it is moderately active, meaning that it flares quite a lot," which might explain the presumed lack of atmosphere, as stated by MIT News.
Lacking an atmosphere means that, hypothetically, one standing on SPECULOOS-3b's surface would see nothing but a dark, expansive void overhead, broken only by the sizable purplish-red star it orbits. This clear view makes the planet an exceptional target for further study by the James Webb Space Telescope, which could reveal detailed surface characteristics. Such insights would be pivotal, as Rackham noted. "We think that the planet is nearly as hot as Venus, so not habitable," he stated. "But depending on how bright that rock is, it could be recently resurfaced due to plate tectonics or volcanic activity, or it could be a planet that's been eroded by space weathering and has a much darker surface," as reported by MIT News.
Backed in part by the European Research Council, Simons Foundation, and Heising-Simons Foundation, this discovery marks a potential leap forward in the field of exoplanetary research, moving towards constraining the surface properties of planets outside our own solar system and potentially unveiling geologic activities alien to what we know on Earth.
