A supernova went off right next to the young Sun – how did it survive?
Meteorites can act as time capsules, preserving molecules from the solar system’s infancy. Certain fingerprints have been detected in these ancient space rocks that suggest a supernova went off right near our neighborhood – but that should have blasted the young solar system away. So how did it survive? A new study proposes an explanation.
Asteroids and comets are basically the crumbs left over from the birth of the solar system, and they can contain some fascinating clues to those early days that we can’t find elsewhere. Scientists have cracked open meteorites that make it to Earth’s surface and found blue crystals preserving a record of the Sun’s rowdy youth, diamonds from long-lost giant planets, fragments of ancient “ocean worlds,” and even grains that predate the Sun.
One of the most intriguing discoveries in meteorites is that of particularly high concentrations of aluminum-26, a radioactive form of the metal. The best explanation for how these got there is a nearby supernova, the explosion thrown off when a massive star dies. But there’s a problem with that story – a supernova with the power to inject this amount of radioactive isotopes would also have thrown off a shock wave strong enough to blast away the young solar system before it got a chance to take hold.
That obviously didn’t happen, since we’re here today to wonder about it. So how did the burgeoning solar system survive such an onslaught? Researchers at the National Astronomical Observatory of Japan (NAOJ) have proposed a new explanation.
It all comes down to how stars form. When regions of gigantic molecular clouds become dense enough, pockets collapse under their own gravity and begin forming stars. These clouds have been seen to stretch into long filaments, with relatively small stars like the Sun forming inside those filaments, while more massive stars – the kind at risk of going supernova – form at the crossroads, where multiple filaments meet.
If this was the case for our Sun, and a star exploded at a nearby filament hub, the forming solar system would have been shielded by the filament it was born in. The team calculated that it would have taken at least 300,000 years for the supernova’s blast wave to break up the filament and destroy our future home. Thankfully, the explosion didn’t sustain that energy for that long. The filament, however, would still have caught the radioactive isotopes and funneled them into the solar system, which is why their fingerprints are still visible in meteorites today.
The researchers say that this model could be observed in action in other areas of the universe currently undergoing star formation.
The research was published in the Astrophysical Journal Letters.