If you've ever had a nasty neighbor—well, the solar system can empathize.
Recent findings by astronomers Leslie Looney and Brian Fields at the University of Illinois at Urbana-Champaign suggest that several billion years ago, a massive star experienced a violent death right next to our solar system. Their research has been accepted for publication in the Astrophysical Journal.
"The supernova was very, very close—way too close to be comfortable," Looney said.
Looney and Fields looked at the composition of several meteorites analyzed by other groups and found they contained daughter elements—products of radioactive decay. Though the researchers had been expecting to find evidence that the meteorites were once radioactive, they also made a more surprising discovery.
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"There were live radioactive elements in meteorites, and these are short-lived," Looney said. "One has to wonder, 'Where did they come from?' because they shouldn't be there."
The radioactive elements could have formed with the solar system, but that seemed unlikely, Looney said, "because there are certain elements you can't make when the sun was being formed."
The researchers concluded that the elements had most likely come from a nearby supernova—an explosion caused by the violent death of a massive star and the main source of elements heavier than oxygen.
The supernova, the researchers concluded, must have been much closer to our sun than any other known stars. This finding suggests that, like the majority of stars, our sun was actually born in a cluster of stars. Though there has previously been little evidence to suggest it, our sun, it seems, was not an only child.
If the solar system did survive a nearby supernova, the event would have implications for theories of planet formation. We know that the planets formed from a planetary disk—a rotating cloud of dense gas that eventually condensed into the solar system. A close supernova implies that planetary disks are more durable than previously thought.
"It is true that one of the interesting things to think about is how the star-forming environment affects the [planet-forming] disk," said Richard Durisen, an astronomer at Indiana University who researches planet formation.
Looney is excited by what his discovery might mean. If planetary disks are durable and can withstand serious stress in star clusters, it may be that more stars have planets than scientists once believed.
"If you have more planets, you have more possible planets with Earth-like water," he said. "Therefore you have more chance for life that's based on water."