(ORDO NEWS) — According to calculations , there are quite a few planets in our Universe that have “strayed” from their parent stars. Now, researchers have discovered the smallest of these, the size of Earth.
When a planet loses its parent star, it becomes an orphan. Finding such objects is extremely difficult, but Polish astronomers managed to do it. Lonely exoplanet became the smallest of its kind.
To date, astronomers have discovered over 4,000 exoplanets. Most of the known exoplanets are unlike those found in our solar system, but they all have one thing in common – they all revolve around the star. However, theories of planetary formation and evolution predict the existence of orphan planets gravitationally unrelated to any star.
But a few years ago, researchers at the University of Warsaw Astronomical Observatory announced that they had found a body in the Milky Way that looked like an orphan planet. Now scientists confirmed the existence of this celestial body and measured its size and mass. It turned out that this is the smallest orphan planet in size comparable to the Earth.
To detect a celestial body, scientists used the method of gravitational microlensing. It allows you to see relatively small celestial bodies, observing the distortions of light that they create when passing in front of the star. The likelihood of detecting such events is very small: according to scientists, if you observe one star, then one microlensing event can be noticed in about a million years.
Instead of observing a single star for a long time, Polish astronomers looked directly behind a huge number of stars closer to the center of the Milky Way. As a result, over 28 years of filming as part of the OGLE project, scientists were able to collect enough data to say unambiguously that the microlensing event they recorded is indeed an orphan planet.
The OGLE-2016-BLG-1928 event lasted only 42 minutes. Analysis showed that there are no stars at least 8 astronomical units (the distance from the Sun to Saturn) from the planet.
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