Super-Earths might be far more common in the Universe than previously thought. A recent study using the KMTNet telescope network has revealed their presence in unexpected locations.
This discovery relies on a technique called gravitational microlensing, which detects planets by observing distortions in the light of distant stars. Researchers have identified super-Earths orbiting at distances comparable to Jupiter's orbit around the Sun—a configuration previously considered rare.
The international team, including scientists from several countries, analyzed data collected by the KMTNet telescopes. These instruments, located in South Africa, Chile, and Australia, continuously monitor millions of stars for microlensing events.
The results suggest that for every three stars in our galaxy, there is at least one super-Earth with an extended orbit. This unexpected abundance challenges current theories of planet formation, which predicted such worlds would be rare at these distances.
Gravitational microlensing offers a unique advantage: it can detect planets regardless of their brightness. This relatively new method has already discovered 237 exoplanets among the more than 5,500 known to date.
The researchers also compared their observations with theoretical simulations. Although progress has been made, the exact formation mechanisms of these super-Earths remain a subject of debate among scientists.
This study, published in
Science, opens new perspectives on the diversity of planetary systems.
What is gravitational microlensing?
Gravitational microlensing is an astrophysical phenomenon predicted by Einstein's theory of general relativity. It occurs when a massive object, such as a star or planet, passes in front of a more distant star from our viewpoint.
This passage warps spacetime around the massive object, bending the light from the background star. This distortion creates a temporary increase in the star's brightness, which can last from a few hours to several months.
Astronomers use these brightness variations to detect otherwise invisible objects, such as planets or brown dwarfs. Microlensing is particularly useful for finding planets located far from their star, where other methods fail.
However, these events are rare and require monitoring millions of stars to capture just a few. Telescope networks like KMTNet are essential for increasing detection chances.
Why are super-Earths so interesting?
Super-Earths, with masses between Earth's and Neptune's, represent a category of planets absent from our Solar System. Studying them can teach us much about the diversity of worlds in the Universe.
These planets can have varied compositions, ranging from rocky worlds similar to Earth to planets covered in oceans or thick atmospheres. Their presence at varying distances from their star raises questions about the conditions needed for planet formation.
The discovery of super-Earths in extended orbits, like those revealed by the KMTNet study, suggests planetary formation mechanisms are more diverse than expected. This could involve poorly understood processes, such as planetary migration or gas accretion at great distances.
Understanding these planets is crucial for assessing the likelihood of finding habitable worlds. Super-Earths, due to their size and diversity, could host environments suitable for life—very different from those we know.