There is one planet we can observe in detail: our own Earth. And sometimes we are lucky enough to find rocks from elsewhere here that we can analyze and use to learn about our solar system’s history. Understanding that history can help us understand not only our own solar system but exoplanetary systems as well. Every piece of information we collect can lead to a better picture of solar system formation, something we seem to talk about a lot on Daily Space. 

Results published in Geochimica et Cosmochimica Acta show that a small meteorite named Acfer 094, which was found in 1990, is an incredibly primitive meteorite from our early solar system, 4.6 billion years old. By analyzing the sulfur and oxygen isotopes in this 85-gram rock, scientists determined that differences in the chemical composition from our Sun were caused by ancient starlight.

The Sun likely formed where massive stars were relatively close, and ultraviolet light from those massive stars broke apart carbon monoxide gas in our protoplanetary disk and irradiated hydrogen sulfide gas, changing the overall composition from what our star contained. So the building blocks for our solar system were affected by starlight from a nearby massive star. 

And we can see evidence of this same effect in proplyds, or protoplanetary disks, found in places like the Orion Nebula, where massive O and B type stars are tearing apart the gas in the disk. That’s a pretty impressive link in the planetary formation chain, and it’s all because of a tiny rock falling to Earth.

More Information

Washington University in St. Louis press release

“Cosmic symplectite recorded irradiation by nearby massive stars in the solar system’s parent molecular cloud,” Lionel G. Vacher et al., 2021 June 25, Geochimica et Cosmochimica Acta