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Kicked Out

February 18, 2017

The Orion Nebula stands halfway up the southern sky a couple of hours after sunset right now. To the eye alone, it looks like a fuzzy star. In reality, though, it’s the birthplace of thousands of stars.

Many of those stars are still in or around the nebula. But at least two that were born in that region are racing away from it at more than 200,000 miles per hour. They probably were kicked out by an encounter with two other stars, which appear just above the nebula.

One of the escapees stands high atop the sky, in Auriga, the charioteer. The other is in the opposite direction from Orion, down near the horizon in Columba, the dove. Under dark skies, that star, Mu Columbae, is visible to the unaided eye.

Simulations show that both stars were ejected from Orion about two-and-a-half million years ago.

The ejection happened after two binary systems passed close together. Each binary contained two big, hot, massive stars.

A study a few years ago found that the encounter split both binaries apart. One star from each system then came together to form a new binary. The remaining star from each binary was given a massive kick away from Orion. One star was hurled northward, while the other was kicked southward.

In the many years since then, both stars have traveled far across the galaxy — one all the way to Auriga, the other to Columba. And they continue to race across the galaxy today, putting even more distance between them and their birthplace.


Script by Damond Benningfield

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