When we imagine a planet, we think of one like ours orbiting a star. But some lead a much more lonely existence, drifting through interstellar space with no sun to call their own. Known as a “rogue” or “free-floating” planetsthese worlds are often difficult to explore. Having no known star or orbit by which to estimate their size, they tend to flew under the radar-until now.
In a new study published V Science On Thursday, scientists reveal how they have measured the mass of one such rogue planet for the first time, a breakthrough that could enable further exploration of these strange, lonely worlds.
Instead of looking at the planet's orbit, a research team led by Peking University's Subo Dong analyzed how the planet's gravity bends light from a distant star in what is known as microlensing, from two separate perspectives: Earth and the now-retired Gaia space observatory.
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According to Dong, the technique is similar to how depth perception in our eyes works: the microlensing event was noticed by Gaia about two hours later than scientists on Earth. This time difference allowed the researchers to measure the distance to the planet and estimate its mass.
“What's really remarkable about this work, and what's really remarkable, is that we've got a ton of these objects for the first time,” says Gavin Coleman, a research fellow at Queen Mary University of London and author of the study. relevant comment also published in Science but did not participate in the study. “This was solely because the authors had both ground-based observations and Gaia looking at observations from two different locations.”
They found that the planet has about the same mass as Saturn. But the results also give hints about his past: “Knowing [its mass] “This is the starting point,” says Dong. “We can begin to understand, okay, what might be the origin, the history of this planet?”
Dong hopes the study will serve as a starting point for further research to better understand these issues. mysterious cosmic bodies. That effort will get a boost later this year with NASA's Nancy Grace Rome Space Telescope, scheduled to launch in September, according to David Bennett, a senior scientist at the University of Maryland, College Park and NASA. A novel capable of imaging the entire sky 1,000 times faster than the Hubble Space Telescope will help identify hundreds of rogue planets. Thanks to this work, researchers will have the opportunity to estimate their mass.
“The door is open to study this new emerging population of planets,” says Dong.
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