A very young Solar System survived an explosion of a supernova that occurred near our newly formed Sun. The event could have destroyed our little corner of the universe if it hadn’t been for a shield of molecular gas.
Aluminum isotopes
Scientists reached this conclusion by studying the isotopes of elements found in meteorites. These space rocks are formed from the same material present when the celestial covers of the Solar System were formed. Therefore, meteors are kind of fossils that allow scientists to reconstruct the evolution of the solar system.
The research team found varying concentrations of a radioactive aluminum isotope in meteorite samples. This information revealed that about 4.6 billion years ago, an additional amount of radioactive aluminum entered our planetary backyard. Best explanation for such an injection of radioactive material is a nearby supernova explosion, said the members of the research team.
Newborn Solar System probably survived a shockwave created by the explosion of a supernova, according to researchers led by astrophysicist Doris Arzoumanian from the National Astronomical Observatory of Japan. The same birth cocoon of the system likely acted as a protective sphere against the shockwave, they added.
Supernova Explosion
Supernova explosions occur when massive dying stars deplete their fuel for nuclear fusion. Their cores can no longer resist gravitational collapse. When the core collapses, it triggers a supernova that disperses heavy elements the star forged throughout its life into space.
This material becomes the building blocks for the next generation of stars. But the shockwave carrying it outward can be strong enough to tear apart any newly formed planetary system nearby.
Stars are born in giant clouds of molecular gas composed of dense tendrils or filaments. Smaller stellar bodies, like the Sun, form along these filaments. Larger stars, like the one that would have exploded in this supernova, tend to form at the points where these filaments intersect. Arzoumanian and the team estimated that the supernova shockwave to break through the dense filament protecting the newborn solar system would have had to occur 300,000 years earlier.
Meteorites as Fossils
Meteorites rich in radioactive isotopes separated from larger bodies in the first 100,000 years of the Solar System while still in this dense filament. The cocoon, therefore, would have acted as a protective shield against the intense radiation emitted by hot and massive stars called OB stars. We’re talking about an amount of energy that could have negatively impacted the formation of planets like Earth.
The new findings suggest that, besides acting as a shield, the filament might have captured and channeled the radioactive isotopes, bringing them into the region around the nascent Sun. The researchers believe their discoveries could be crucial for understanding the formation and evolution of stars and their planetary systems.
“This scenario could have several important implications for understanding the formation, evolution, and properties of stellar systems” the team wrote in the study (ref.) published in April in the Astrophysical Journal Letters. “The host filament could play a significant role in shielding the young solar system from the far-ultraviolet radiation of OB stars. This would cause the protostellar disk to evaporate, influencing its final size. This would have a direct impact on the formation of planets within the disk” they added.