Binary stars could be causing massive planetary collisions

Three different sets of binary stars - two stars locked in orbit around each other - are surrounded by huge clouds of dust. Astronomers suspect these are the remains of gigantic planetary collisions caused by the binary stars' intense gravity.

This particular type of binary star system, known as RS Canum Venaticorums or RS CVns for short, features almost zero separation between the two stars. They can be separated by as little as two million miles, which is only a fiftieth of the distance between the Sun and the Earth and about eight times the distance between the Earth and the Moon. The two stars orbit each other once every few days, with a face of each star permanently locked and facing the other.


Remarkably, such a system doesn't rule out the possibility of planets forming, even ones that could support life. But their closely linked orbits do create problems, as the stars in such a system spin much, much faster than that of our Sun, creating tremendous magnetic fields and incredibly strong stellar winds. These forces conspire to slowly bring the two stars closer together, which could spell catastrophe for any planets revolving around them.

As the stars get closer together, their gravitational fields shift, which throws off how the orbits of their planets and other bodies like comets. This gravitational jostling makes massive collisions far, far more likely. These impacts could be traumatic enough to destroy entire planets. Astronomers suspect those massive dust clouds found around these binary stars could well be the remnants of planets smashed together by the stars' shifting gravity.

Astrophysicist Jeremy Drake offered a dramatic interpretation of these findings:

"This is real-life science fiction. Our data tell us that planets in these systems might not be so lucky — collisions could be common. It's theoretically possible that habitable planets could exist around these types of stars, so if there happened to be any life there, it could be doomed."


The binary systems in this study are all about one to two billion years old, which is roughly the same time in the Sun's history that the earliest forms of life emerged on Earth. At that point in their lives, stars are considered mature, and it's rare to find such large clouds of dusts around stars that old. Something chaotic and unexpected must be preventing those dust clouds from dissipating, perhaps even adding to the size of the clouds over time. It's a grim possibility, but colliding planets are the most likely explanation.

[The Astrophysical Journal]


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