Scientists have found a planet about the size of Earth that is constantly exposed to radiation; its atmosphere has long since corroded away, leaving it bare. While astronomers are not interested in life as we know it because they might be able to study the geology of a planet outside our solar system for the first time, life as we know it cannot live on this scorching planet.
SPECULOOS-3 b, the newly discovered exoplanet, is a rocky planet located around 55 light-years away from Earth. Days and nights on the planet are limitless, but it zips around its host star every 17 hours. Similar to how the moon is to Earth, astronomers believe the planet is tidally locked to its star. The nightside is imprisoned in perpetual darkness, while a single dayside is always directed toward the star.
The exoplanet’s star, a red dwarf star approximately the size of Jupiter that is 7 billion years old, regularly emits radiation that causes the planet to heat up to Venus-like levels, according to telescope measurements. According to scientists’ latest analysis, which was published on May 15 in the journal Nature Astronomy, whatever atmosphere that the planet may have had may have easily gone into space long ago and left behind a sizzling boulder that was devoid of air.
“Life as we know it could not emerge on the surface of the planet—atmosphere or not—because it could not sustain large amounts of water in liquid form,” said Michaël Gillon, the primary author of the study and an astronomer at the University of Liège in Belgium, to Live Science. “It is a bare rock planet like Mercury.”
The researchers stated that although though SPECULOOS-3 b is uninhabitable by life, it is sufficiently close to Earth to allow for in-depth investigations on its chemical composition, which could determine whether the planet was ever geologically active.
For example, future observations with the James Webb Space Telescope (JWST) will be able to verify whether or not volcanoes have erupted on the planet. That might shed light on how rocky planets, such as SPECULOOS-3 b, originate around dim, luminous stars and whether some of them are potentially habitable even though they are near their sun.
Gillon stated that the team “searched intensively” for planetary siblings of SPECULOOS-3 b in the same solar system but was unable to locate any. He mentioned the possibility that those extra planets exist, but they are either too small or too far away from their host star to be visible.
Around a Cold Star is a Hot Planet
Since 2011, Gillon and his associates have used a network of six telescopes dispersed around Chile, the Canary Islands, and Mexico to identify SPECULOOS-3 b. The network is known as the Search for Planets Eclipsing Ultra-Cool Stars, or SPECULOOS. Its name is derived from a spiced shortbread from Belgium that is typically presented to kids on December 6th in honor of St. Nicholas Day.
Finding rocky planets around ultracool dwarf stars, whose small size makes it simpler for telescopes to find planets in orbit, is the primary objective of the project. Not only are they hundreds of times dimmer and thousands of degrees colder than the sun, but they also burn up their fuel slowly and have a much longer lifespan—roughly 100 billion years. (When the sun dies in around 4.5 billion years, it will be about 10 billion years old.)
Remarkably, “they are expected to be the last stars still shining in the universe,” stated Amaury Triaud, the co-author of the study and an exoplanetology professor at the University of Birmingham in England. According to the experts, their exceptionally long lifespans provide windows of opportunity for life to arise on planets within their systems.
Nevertheless, it is challenging to examine them due to their great faintness. A SPECULOOS robotic telescope in Mexico monitored telltale dips in the host star’s light constantly for five nights in 2021 in order to find SPECULOOS-3 b. The study discovered that the first indications of the orbiting newfound planet appeared then and were verified a year later.
“There would be no blue sky or clouds if there is no atmosphere — it would just be dark, like on the surface of the moon,” MIT research scientist and study co-author Benjamin Rackham stated in a different MIT statement. “And the ‘sun’ would be a big, purplish-red, spotted, and flaring star that would look about 18 times as big as the sun looks to us in the sky.”
According to Gillon, SPECULOOS-3 b is the project’s ninth discovery of this kind of planet, and many more should be discovered in the years to come. The newly discovered SPECULOOS-3 b “is an excellent target for JWST,” according to Gillon, similar to the planets previously spotted by the project, including a family of seven in the well-known TRAPPIST-1 system, some of which are thought to be possibly habitable.
“With this world, we could basically start doing exoplanetary geology,” MIT assistant professor of planetary sciences and research co-author Julien de Wit stated in a release regarding the MIT study. “How cool is that?”
