Astronomers have identified a solar system in deep space where life as we know it may have developed. Astronomers discovered two super-Earths orbiting a cool star, some 100 light-years from Earth.
Two “super-Earth” planets have been discovered orbiting LP 890-9, a small, ultracool dwarf about 100 light-years from Earth, by an international research team, including astronomers from the University of Birmingham. One of the newly found exoplanets is believed to orbit its start in the so-called habitable zone. The star, also known as TOI-4306 or SPECULOOS-2, is the second-coolest planet host star after TRAPPIST-1. It hosts an alien world that astronomers consider the second-most favorable target among all the potentially habitable terrestrial planets known so far. In other words, there are chances that this world could have developed life.
LP 890-9b, the first planet and the inner planet of the solar system, has a diameter of about 30% that of Earth and orbits the star in just 2.7 days. TESS, NASA’s space mission that searches for exoplanets orbiting nearby stars, initially identified this planet as a possible planet candidate. Researchers at the University of Birmingham used the SPECULOOS telescopes to confirm and characterize this candidate. Additionally, SPECULOOS researchers searched the system for transiting planets that TESS would have missed.
By simultaneously monitoring the brightness of thousands of nearby suns, TESS searches for exoplanets using the transit method, looking for slight dimmings that might be caused by planets passing in front of their stars,” explains Laetitia Delrez, lead author and postdoctoral researcher at the University of Liège. “However, a follow-up with ground-based telescopes is often necessary to confirm the planetary nature of the detected candidates and to refine the measurements of their sizes and orbital properties.”
In the case of very cold stars, such as LP 890-9, since TESS is unable to observe their near-infrared light, this follow-up is particularly important. A SPECULOOS telescope on the island of Tenerife and at the Paranal Observatory in Chile are equipped with near-infrared cameras that enable precise observations of this type of star. SPECULOOS seeks to locate terrestrial planets that might be habitable, transiting some of the smallest, coolest stars in our solar neighborhood, such as TRAPPIST-1, discovered in 2016. Michael Gillon, a researcher at Liège University, explains.
Moreover, he heads the SPECULOOS project. With big telescopes like the James Webb Space Telescope (JWST), it is possible to examine such planets’ atmospheres and search for chemical signs of life, which is an important part of this strategy.” The state-of-the-art telescope recently detected carbon dioxide for the first time on a distant alien world. As a result of the observations made by SPECULOOS of LP 890-9, not only was the first planet confirmed but also an unknown planet was detected and confirmed. The second planet, LP 890-9c (renamed SPECULOOS-2c by the SPECULOOS scientists), is about the same size as the first (about 40% larger than Earth), but it orbits around the sun about 8.5 days longer than the first planet. MuSCAT3 in Hawaii later confirmed that the planet’s orbital period places it in the so-called habitable zone, a region in space around a star where liquid water is likely to exist on the planet’s surface.
According to Amaury Triaud, professor of exoplanetology at the University of Birmingham and head of the SPECULOOS working group that scheduled the observations leading to the discovery of the second planet, a planet with similar geological and atmospheric conditions would have a surface temperature allowing water to remain liquid for billions of years. “This gives us a license to observe more and find out whether the planet has an atmosphere, and if so, to study its content and assess its habitability.”
It is expected that this planet’s atmosphere will be studied with the JWST in the future and that it appears to be the second-most favorable target among all of the potentially habitable terrestrial planets known so far, trailing only TRAPPIST-1 (for which Professor Triaud co-discovered). According to Professor Triaud, detecting as many temperate terrestrial planets as possible is important to study the diversity of exoplanet climates and ultimately measure how often life appears in the Cosmos.
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