Unraveling the Mystery of a Meteorite Reveals the Solar System’s Origin Story
Washington DC-The violent event that likely preceded the formation of our solar system holds the solution to a long-standing meteorite mystery, according to new work by Carnegie’s Alan Boss published in The Astrophysical Journal.
The raw material from which our solar system was built was scattered when the shock wave of an explosive supernova injected material into a cloud of dust and gas, causing it to collapse in on itself . Following this event, most of the injected material was pulled by gravity to the center of the vortex, where the intense pressure buildup allowed nuclear fusion to begin, and the Sun was born. The young star was surrounded by a spinning disc of leftover gas and dust, from which planets and other bodies in the solar system, some of which eventually separated to form asteroids and meteorites, merged.
“The mystery stems from studying the isotopic composition of meteorites, which can be used as a laboratory to test theories of solar system formation and evolution,” says Boss.
Isotopes are versions of elements with the same number of protons, but a different number of neutrons. Sometimes, as is the case with radioactive isotopes, the number of neutrons present in the nucleus can make the isotope unstable. To gain stability, the isotope releases energetic particles, which modify its number of protons and neutrons, transmuting it into another element, called the daughter isotope.
Boss added: “Because we know exactly how long this process takes for different radioactive isotopes, measuring the amount of progeny in meteorites can tell us when, and possibly how, they formed.”
For example, the iron isotope with an atomic weight of 60 is only produced in significant quantities by a supernova explosion and it takes 2.6 million years for half of the atoms to decay – its se -called “half-life” – into its daughter isotope. , nickel-60. So when significant amounts of nickel-60 are found in primitive meteorites called carbonaceous chondrites, it tells researchers that the raw material from which the chondrite was constructed contained the remnants of a supernova explosion that occurred. produced only a few million years before its formation.
The chondrite record can be used to confirm the supernova origin story for our solar system. But other less primitive, non-carbonaceous meteorites do not have this iron-60 composition, which means that the material from which they formed did not come from a stellar explosion. So where does it come from?
“No physical explanation has been offered for this dramatic change.” says the boss.
He perfected sophisticated models of the formation of our solar system for several decades and was one of the originators of the supernova injection origin story. By extending the time period reflected in his simulations, he was able to show that after triggering the collapse that fed the chondrites with iron-60, the supernova’s shock front sweeps the interstellar dust past the resulting disk. and accelerates the resulting protostar to a speed of several kilometers per second. That’s enough to cause the young Sun to encounter a new patch of interstellar matter depleted in iron-60 and other isotopes generated by supernovae a million years from now.
“Having worked on the problem of supernova triggering and injection since the mid-90s, it was amazing to finally be able to relate this model to the meteoric evidence,” Boss concluded. “It concludes this tale with a neat arc.”