A newly discovered exoplanet is now our second-best target for the Webb telescope, scientists say

Scientists have discovered two “super-Earth” exoplanets, one of which is in its star’s habitable zone. That means liquid water could exist on its surface.

The planet, known as LP 890-9c or SPECULOOS-2c, was found around a red dwarf star about 100 light-years from Earth in the constellation of Eridanus. Cooler than our Sun, red dwarf stars are by far the most abundant in our Milky Way, making up about 80% of the population, as far as astronomers know.

Among the potentially habitable terrestrial planets currently known to astronomers, LP 890-9c appears to be the second most favorable target, according to its discoverers. It was found accidentally while scientists were reviewing their initial discovery of another exoplanet around the same star, designated LP 890-9/TOI-4306/SPECULOOS-2. It’s the second coolest star to host planets, after the famous TRAPPIST 1 star system, which hosts up to seven planets and has been dubbed “Solar System 2.0.”

Published in the magazine Astronomy & Astrophysicsresearchers discovered the first planet, LP 890-9b, around the star with NASA’s $287 million Transiting Exoplanet Survey Satellite (TESS) and tracked it with ground-based telescopes from the SPECULOOS consortium in Chile and Tenerife. Orbiting its star in 2.7 days, LP 890-9b is too hot to hold liquid water.

Fortunately, TESS has limited detection capabilities, requiring double-checking of observations. It finds exoplanets by detecting a slight dimming of a star as a planet — or its shadow — wanders across its surface. “Follow-up with ground-based telescopes is often necessary to confirm that the candidates discovered are indeed planets and then to learn more about their properties,” said Dr. Laetitia Delrez, FNRS postdoctoral researcher at the University of Liège, Belgium and lead author of the study. “This tracking is particularly important for relatively cold stars like TOI-4306, which emit most of their light in the near-infrared and for which TESS has a rather limited sensitivity.”

Could LP 890-9c actually be habitable? This is unknown. It’s a “super-Earth,” but don’t assume it’s like Earth, just slightly larger. LP 890-9c is likely rocky and about a third larger than Earth, but it takes just 8.5 days to orbit its star. As it orbits a star much cooler than our sun checking out.

“Although this planet orbits its star very closely, at a distance about 10 times shorter than that of Mercury orbiting our Sun, the amount of stellar radiation it receives is still small and could indicate the presence of liquid water on the surface of the planet enable. provided it has a sufficient atmosphere,” said Francisco J. Pozuelos, a researcher at the Institute of Astrophysics of Andalusia and one of the paper’s key co-authors. “That’s because the star LP 890-9 is about 6.5 times smaller than the Sun and has a surface temperature half that of our star. This explains why LP 890-9c, despite being much closer to its star than Earth is to the Sun, could still have conditions suitable for life.”

Before this “super-Earth” is even declared as possibly Earth-like, many more observations need to be made, particularly by the James Webb Space Telescope (JWST), which could help researchers study its atmosphere – if there is one.

The study’s authors believe this exoplanet could be ripe for JWST atmosphere detection. “LP 890-9c is near the inner limit of the habitable zone and therefore could have a particularly water vapor-rich atmosphere, which would then amplify its atmospheric signals,” Delrez said. She added that the discovery of LP 890 -9c is a unique opportunity to learn more about the exact location of the inner limit of a star’s habitable zone.

However, the habitable zone around a star where liquid water could theoretically exist — between the “snowline” too far away and the “boiling zone” too close — doesn’t guarantee anything. “Our neighboring planet Venus, which is, so to speak, a CO2-rich pressure cooker with a temperature of almost 500°C, is also located in the vicinity of this so-called habitable zone around the sun,” says Dr. Robert Wells from the University of Bern and the NCCR PlanetS and co-author of the study.

So far, TESS has discovered about 5,000 planets and planet candidates. In total, TESS is expected to find around 12,519 exoplanets.

I wish you clear skies and big eyes.