Belgian astronomers discover Earth-sized planet near ultracool star
Astronomers from Belgium have made a discovery that could deepen our understanding of the universe. They observed a planet of Earth-like size near an ultracool dwarf star situated 55 light-years away from us. Although this star is significantly cooler than our Sun, the planet in close proximity to it is exposed to intense radiation.
This discovery is the responsibility of the research team from the University of Liège, leading the SPECULOOS (Search for Planets EClipsing ULtra-cOOl Stars) project. The experts identified a planet named SPECULOOS-3 that orbits the ultracool dwarf. This is the second planetary system discovered around such a star.
A planet of Earth-like size
Ultracool dwarfs, as explained by scientists, are the least massive stars in the universe. Their sizes are comparable to large planets like Jupiter. They are much cooler than the Sun, have a mass 90% less than the Sun’s, and are about 100 times dimmer. Moreover, they live roughly 100 times longer than our Sun and will be the last stars to survive in the future cooling universe.
Despite ultracool dwarfs being more numerous in space than stars like the Sun, they are relatively poorly understood. This is because they emit only a small amount of light. Particularly, little is known about the planets that orbit them, even though they are believed to constitute a significant portion of all Milky Way planets.
The SPECULOOS project, coordinated by Prof. Michaël Gillon from the University of Liège, was explicitly created to search for planets orbiting ultracool dwarfs. Scientists look for planets passing in front of the star, which allows their detection but usually requires weeks of observation for each individual star. Therefore, the project’s creators use a network of automated telescopes to speed up the observation process significantly.
The newly discovered planet SPECULOOS-3 b is 55 light-years from our Solar System, so we can consider it our cosmic neighbor.
Although the star around which the planet orbits is relatively cool, the very close orbit means the planet is bombarded with high-energy radiation. "In such an environment, the presence of an atmosphere around the planet is highly unlikely" notes Prof. Julien de Wit from MIT, who is involved in the project.
"The fact that this planet has no atmosphere could be a plus in several respects. For example, it could enable us to learn a great deal about ultra-cool dwarf stars, which in turn will make possible more in-depth studies of their potentially habitable planets," he adds.
According to researchers, SPECULOOS-3 is an excellent target for the James Webb Telescope. "With the JWST, we could even study the mineralogy of the planet's surface!"," emphasizes Dr. Elsa Ducrot, co-author of the discovery.
"This discovery demonstrates the ability of our SPECULOOS-North observatory to detect Earth-sized exoplanets suitable for detailed study. And this is just the beginning! Thanks to the financial support of the Walloon Region and the University of Liège, two new telescopes, Orion and Apollo, will soon join Artemis on the plateau of the Teide volcano in Tenerife, to speed up the hunt for these fascinating planets," concludes Prof. Gillon.
