Stars in the universe take planets away from each other

(ORDO NEWS) — Approximately every 50th planet may have been stolen from another star, including this could happen in the solar system, writes May 25 in the scientific journal New Scientist.

It has been speculated for some time that planets with extremely wide orbits may have been born elsewhere because they are difficult to form at such distances from the central star. For example, the ninth planet in our solar system (Pluto) could be a stolen exoplanet captured from a passing star.

Such events can occur early in the life of stars, when they are born in dense clusters from the same cloud of dust and gas.

These clusters can contain thousands of stars, often relatively close together, before they drift apart in space. If planets form around these young stars, they can “leave ship” early in their existence when other stars pass nearby.

Emma Duffern-Powell and her colleagues at the University of Sheffield in the UK found out how often this can happen. They modeled a cluster of 1,000 stars, each separated by a third of a light year. Half of them were given a single planet with an orbit as distant as that of Neptune.

The results showed that about 2% of the planets were “stolen” in the first 10 million years of the existence of the cluster, that is, directly redistributed among the stars before they “spread”.

Another 2% were “captured”, being in the state of free-floating planets, not tied to a star. The rest either stabilized in orbit around their star, or were thrown into the galaxy in a collision with other stars.

For a star to capture a planet from another star, it would need to move within a few hundred astronomical units (AU), each corresponding to the distance from the Earth to the Sun.

Captured planets will be in wider orbits than stolen planets, says study co-author Richard Parker. “In the presence of a very energetic interaction, such a planet should have a rather small orbit,” he noted.

Both captured and stolen planets will also have less circular and more inclined orbits – those that are at an angle to the plane of the system. We can identify such planets by mapping their orbits, the researchers say.

Matthew Kenworthy of the University of Leiden in the Netherlands says he has already come across proof of the existence of such worlds. “My group has identified three planets that are at a distance of 100 to 500 AU. That is, and according to these calculations, it turns out that they do not revolve around the parent star.

At the moment, we have only received direct images of a few dozen celestial bodies, but this number should increase as more powerful telescopes, such as the European Extremely Large Telescope, become operational in the coming years, the scientist said.


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