New research reveals super-Earths are common in distant orbits

Time of India

27-04-2025

Microlensing reveals distant worlds
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A recent international study has found that super-Earth exoplanets — those larger than Earth but smaller than Uranus or Neptune — are significantly more common across the universe than previously assumed.The research team, led by astronomers from Ohio State University , Harvard University, and institutions in China and Korea, uncovered evidence that these planets are not restricted to tight orbits around their stars. Instead, many can exist as far out as Jupiter does in our own solar system.The discovery was made through gravitational microlensing , a method that detects the bending and magnification of a distant star's light caused by an intervening object such as a planet. This allowed the team to spot OGLE-2016-BLG-0007, a super-Earth around twice the mass of our own planet, orbiting at a distance wider than Saturn's."This study suggests that for every three stars, there is likely at least one super-Earth with a Jupiter-like orbital period," said Andrew Gould, professor emeritus of astronomy at Ohio State University and co-author of the study. He added, "We are beginning to realise just how abundant these massive worlds are across the cosmos."By leveraging microlensing, astronomers have opened a window into finding planets that standard detection methods often miss, particularly those in more distant orbits.Perhaps most striking is how the findings challenge long-standing models of planetary formation . Traditionally, scientists believed that gas giants like Jupiter and Saturn grew through a process called runaway gas accretion. This study suggests the picture might be more complicated."We cannot yet distinguish between the two leading theories of planet formation," explained Gould. "While the dominant theory suggests gas-giant formation occurs through runaway gas accretion, other researchers propose a combination of accretion and gravitational instability. Our study adds to the complexity of these models."The results suggest that both formation pathways might be active in different environments, forcing scientists to rethink assumptions about how planets form across different types of star systems.The research would not have been possible without the Korea Microlensing Telescope Network (KMTNet), a system of telescopes located in South Africa, Chile, and Australia. This network was designed to observe millions of stars continuously, searching for rare microlensing events.Finding such events is no small task. "Finding a microlensing star event is already difficult. Finding one with a planet is even harder," said Richard Pogge, a co-author of the study and professor of astronomy at Ohio State University. He added, "We need to observe hundreds of millions of stars to detect even a handful of these microlensing signals."The technology powering KMTNet's precise measurements was built at Ohio State's Imaging Sciences Laboratory, ensuring that every fleeting anomaly could be captured and studied.To date, only 237 exoplanets have been discovered using microlensing, out of over 5,000 identified through various methods. However, astronomers are confident that improvements in technology will make detecting such distant planets increasingly common.Beyond the discovery of more super-Earths, the study offers broader insights into the architecture of planetary systems . It highlights that planets can be grouped by mass and composition, and points to gaps in the distribution of certain types of planets."This study was a major step forward," said Gould, adding, "Scientists have long known that smaller planets are more common than large ones, but within this pattern, we've found excesses and deficits, offering new insights into planetary distribution."Understanding these gaps could help scientists piece together how planets form, migrate, and survive in their cosmic environments. It also brings us closer to answering bigger questions about how common Earth-like worlds — and perhaps life — might be."We're reconstructing not only the history of the universe but also the processes that govern it," said Pogge. "Bringing these pieces together into a coherent picture has been incredibly rewarding."Published in the journal Science, the study marks a significant milestone in exoplanet research . It was supported by several key institutions, including the National Science Foundation, Tsinghua University, the National Natural Science Foundation of China, and the Harvard-Smithsonian Center for Astrophysics.With global collaborations strengthening and technologies sharpening, astronomers expect even more surprising discoveries about the types and distributions of planets orbiting distant stars.Each new finding not only deepens our knowledge of the universe but also expands the possibilities for future exploration and, perhaps one day, the search for life beyond Earth.