Super-Earths - larger planets similar to Earth - are much more common in the universe than scientists previously thought, according to a groundbreaking microlensing study using the KMTNet telescope. Researchers have discovered that these planets can orbit their stars to vast distances, similar toJupiter and other gas giant planets hint at the rich hidden alien worlds.
Taking advantage of rare cosmic alignments and light anomalies, the team not only discovered new planets but, fueled by international collaboration and innovative telescope technology, began to piece together the mysterious processes of planet formation.
An international team of astronomers using the Korean Microlensing Telescope Network (KMTNet) has discovered that super-Earth exoplanets are much more common in the universe than previously thought.
By analyzing the subtle light distortions caused by the newly discovered planet's host star and comparing their findings to a larger data set from the KMTNet Microlensing Survey, the researchers found that super-Earths could exist at similar distances from their stars as our gas giants are from the Sun, explained study co-author Andrew Gould, professor emeritus of astronomy at The Ohio State University.
"Scientists know that there are more asteroids than large ones, but in this study we were able to show that there are excesses and deficiencies in this overall pattern," he said. "It's very interesting."
While planets orbiting close to their stars are relatively easy to detect, finding planets with wider, more distant orbits is much more difficult. Even so, the team estimates that for every three stars in the Milky Way, there is likely to be at least one super-Earth with a long orbital period similar to Jupiter's. Their findings suggest that these giant, rocky planets may be a common feature of planetary systems throughout the universe — a conclusion that Gould said could help advance the field of planetary microlensing research that he helped pioneer.
The study's findings were made through microlensing, an observational effect that occurs when the presence of matter causes a detectable distortion of the fabric of space-time. When a foreground object, such as a star or planet, passes between the observer and a more distant star, light is bent away from the source, causing a noticeable increase in the object's brightness that can last from a few hours to a few months.
Astronomers can use these brightness fluctuations, or brightness bumps, to help locate alien worlds that are different from our own. In this case, microlensing signals were used to locate OGLE-2016-BLG-0007, a super-Earth with a mass ratio roughly twice that of Earth and an orbit wider than Saturn.
These observations allowed the team to divide exoplanets into two categories: one consisting of super-Earths and Neptune-like planets, and another consisting of gas giants like Jupiter or Saturn. This discovery opens new doors in planetary system science: a better understanding of the distribution of exoplanets could reveal new insights into their formation and evolution.
The study, led by researchers from China, South Korea and the Harvard and Smithsonian Institutions in the United States, was recently published in the journal Science.
To explain their findings, the researchers also compared their findings with predictions from theoretical simulations of planet formation. Their results suggest that while exoplanets can be divided into categories based on mass and composition, the mechanisms by which they are created may differ.
"The leading theory for gas giant planet formation is through runaway gas accretion, but others believe it could be either accretion or gravitational instability," Gould said. "We don't think we can differentiate between the two yet."
Doing so will likely require acquiring large amounts of long-term data from specialized systems like KMTNet and other similar microlensing instruments, said Richard Pogge, another co-author of the study and a professor of astronomy at Ohio State University.
"Finding microlensed star events is difficult. Finding a microlensed star with a planet is even harder," he said. "We would have to observe hundreds of millions of stars to find even a hundred such stars."
This alignment is extremely rare, and of the more than 5,500 exoplanets discovered so far, only 237 have been identified through microlensing technology. Today, with three powerful custom-built telescopes in South Africa, Chile and Australia, the KMTNet system helps scientists regularly search for these amazing events in the universe, Pogue said.
Most notably, scientists at Ohio State University's Imaging Science Laboratory designed and built the Korea Microlens Telescope Network Camera (KMTCam), which the system relies on to identify exoplanets. Pogue said that as technology continues to develop, global collaborations like this will transform the vision of scientific theory into real discoveries.
"We're like paleontologists, reconstructing not just the history of the universe we live in, but also the processes that governed it," he said. "So it's very satisfying to be able to bring those two parts together into one picture."
Compiled from /ScitechDaily