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Exiled planet linked to stellar flyby 3 million years ago


Simulation of a binary star flyby of a young planetary system. UC Berkeley and Stanford astronomers suspect that such a flyby altered the orbit of a planet (in blue) around the star HD 106906 so that it remained bound to the system in an oblique orbit similar to that of a proposed Planet Nine attached to our own solar system. (Paul Kalas animation)

Some of the peculiar aspects of our solar system — an enveloping cloud of comets, dwarf planets in weird orbits and, if it truly exists, a possible Planet Nine far from the sun — have been linked to the close approach of another star in our system’s infancy that flung things helter-skelter.

But are stellar flybys really capable of knocking planets, comets and asteroids askew, reshaping entire planetary systems?

UC Berkeley and Stanford University astronomers think they have now found a smoking gun.

A planet orbiting a young binary star may have been perturbed by another pair of stars that skated too close to the system between 2 and 3 million years ago, soon after the planet formed from a swirling disk of dust and gas.

If confirmed, this bolsters arguments that close stellar misses help sculpt planetary systems and may determine whether or not they harbor planets with stable orbits.

“One of the mysteries arising from the study of exoplanets is that we see systems where the planets are misaligned, even though they are born in a flat, circular disk,” said Paul Kalas, a UC Berkeley adjunct professor of astronomy. “Maybe a cosmic tsunami hit these systems and rearranged everything about them, but we haven’t had proof. Our paper gives rare observational evidence for one of these flybys gently influencing one of the planetary systems in the galaxy.”

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TAGS: Paul Kalas