What To Know
- Although the presence of an atmosphere is unlikely, astronomers are excited about the possibility of studying the planet as it passes behind its star several times with the James Webb Space Telescope (JWST).
- These observations could indeed confirm the presence or absence of an atmosphere and, if it is absent, this would allow the study directly the rocky surface of the planeta first in the history of astronomy.
- By understanding the conditions of habitability around a star as common as ultracool dwarfs, we could then gain crucial information on the likelihood of life in the galaxy and beyond.
Astronomers have announced the discovery of SPECULOOS-3b, an Earth-sized planet orbiting an ultracool dwarf star, a star only slightly larger than Jupiter. It is the second known system of its kind, the first being the famous TRAPPIST-1, which is home to seven Earth-sized planets. Located at a distance of 55 light-years, this new system offers a unique opportunity for exploration.
Earth-sized planet discovered around small star
THE red dwarfs are the most common stars in the Universe. They are characterized by their small size, relatively low mass and relatively low temperature compared to other types of stars. Despite their name, they can appear orange or even yellowish due to their low surface temperature. These stars are also extremely long-lived and burn their fuel at a very slow rate. Some red dwarfs can burn their hydrogen for tens of billions of yearswhich then makes them potentially capable of supporting life for extremely long periods. Due to their long lifespan, their abundance in the Milky Way and their relative stability, red dwarfs have thus become targets of major interest in the search for potentially habitable exoplanets. The star around which this new planet orbits, named SPECULOOS-3bhas a surface temperature twice as cold as the Sun, making it approximately a thousand times darker. We also know that the planet is closely linked to its star. Indeed, SPECULOOS-3b completes a full revolution in just seventeen hours and is exposed to sixteen times more radiation per second than Earth. This extreme proximity probably means that the planet is locked by the tides with one side always plunged into perpetual night and the other constantly illuminated. Astronomers have been able to characterize the star and estimate its age at around seven billion yearsmaking it a stellar host that is neither too young nor too old.
Illustration of a planet around a red dwarf. Credits: dzika_mrowka/iStock
An observation opportunity
Although the presence of an atmosphere is unlikely, astronomers are excited about the possibility of studying the planet as it passes behind its star several times with the James Webb Space Telescope (JWST). These observations could indeed confirm the presence or absence of an atmosphere and, if it is absent, this would allow the study directly the rocky surface of the planeta first in the history of astronomy. Julien de Wit, associate professor of planetary sciences at MIT, emphasizes the importance of this discovery. He says that SPECULOOS-3b is the first planet for which we can consider constraining surface properties beyond the Solar System. He also emphasizes that understanding the composition of these extrasolar worlds is crucial for determining their habitability and assessing the likelihood of life elsewhere in the Universe. This discovery opens up exciting new perspectives for the study of exoplanets and the search for life beyond our Solar System. By understanding the conditions of habitability around a star as common as ultracool dwarfs, we could then gain crucial information on the likelihood of life in the galaxy and beyond. Details of the study are published in the journal Nature Astronomy.
