Two Earth-like planets have been identified, including one which may hold the conditions necessary for life to flourish.
The two exoplanets, LP 890-9b and LP 890-9c, were detected 100 light-years away, orbiting the star LP 890-9 — and have since been dubbed “super-Earths” for their similarities to our home planet, though somewhat more massive.
Based on earlier findings by NASA’s Transiting Exoplanet Survey Satellite (TESS), researchers at the University of Birmingham in the UK used their SPECULOOS telescope — which stands for “Search for habitable Planets Eclipsing ULtra-cOOl Stars” — to confirm the habitability of these two planets.
Naturally, scientists turn to our own place in the solar system when searching for factors that contribute to life, such as the exoplanet’s size and distance from its host star, as well as that star’s size and temperature.
“The habitable zone is a concept under which a planet with similar geological and atmospheric conditions as Earth, would have a surface temperature allowing water to remain liquid for billions of years,” said professor of Exoplanetology Amaury Triaud, whose SPECULOOS team recently confirmed the existence of LP 890-9c, as well as the habitability of its sister planet. Their work is forthcoming in the journal Astronomy & Astrophysics, according to a university news release.
Its star, also called TOI-4306, or SPECULOOS-2, is the second coolest star known to host planets — behind TRAPPIST-1, which boasts seven Earth-sized planets. Stars like these, including our Sun, are believed to be best for nurturing life on their orbiting planets — because the hotter they burn, the harder it is for life to survive.
That’s also what makes them so much harder to detect.
“TESS searches for exoplanets using the transit method, by monitoring the brightness of thousands of stars simultaneously, looking for slight dimmings that might be caused by planets passing in front of their stars,” said lead report author Laetitia Delrez, a researcher at the University of Liège who contributed to the findings. Delrez explained that “a follow-up with ground-based telescopes” can help find what TESS misses due to its limited sensitivity to light in the near-infrared range, which is emitted by colder stars, including LP 890-9.
Researchers further detailed the viability of LP-890-9’s two planets. Its nearest satellite, LP 890-9b, is about 30% larger than Earth, and completes an orbit in 2.7 days — a bit too quick to sustain life, scientists said.
But the system’s outer planet, LP 890-9c, at 40% larger than Earth, orbits about every 8.5 days, which puts it in a “habitable zone” — also often referred to as the “Goldilocks zone” — relative to its star.
LP 890-9c as well as the TRAPPIST-1 planets will be the SPECULOOS telescope’s most favorable targets for upcoming analysis, according to Triaud, who took part in the discovery of both systems.
“It is important to detect as many temperate terrestrial worlds as possible to study the diversity of exoplanet climates, and eventually to be in a position to measure how frequently biology has emerged in the Cosmos,” he said.