Back in the 1950s astronomers discovered a strange population of stars on the lam. Known as OB runaways, these massive stars tear through space at surprisingly high speed—sometimes hundreds of kilometers per second.
How they got going so fast is an open question. It's been proposed that other, exploding stars could be the reason. A supernova, after all, packs enough punch to launch a neighboring star outward at high speed. But a new study published online by the journal Science supports an alternative idea. [Michiko S. Fujii and Simon Portegies Zwart, "The Origin of OB Runaway Stars"]
The mechanism involves a bully binary—that's the astronomers' actual language. The bully is a pair of supersize stars orbiting each other within a larger star cluster. If a third star ventures too close, the bully binary flings it clear like a slingshot. Voila! A runaway. According to the new study, bully binaries form naturally and can each fling out dozens of runaways. And the number of massive stars ejected this way matches up well with actual observations of OB runaways.
So who can blame the runaway stars for fleeing an unfair fight? As it's been said: "Discretion is the better part of valor."
[The above text is a transcript of this podcast.]