Nearby Star-forming Region Yields Clues to the Formation of our Solar System

A joint Austrian-American research team has managed to solve a 50-year-old mystery in the astronomical community regarding the source of radioactive isotopes in our solar system. Is it from a supernova or stellar winds from a nearby object?

The results, which were published in the journal Nature Astronomy and announced by the University of California Santa Cruz, participating in the study, came in an official press release on August 16; To say that the 68% greater probability is that the source of these isotopes is primarily a supernova, but with many other sources.

Supernovae are massive explosions that occur in the final stages of the life of giant stars, with a mass greater than 8 suns, as we know them, and they are so massive that we can see them at a distance of tens of millions of light years.

First author John Forbes at the Flatiron Institute’s Center for Computational Astrophysics said data from space-based gamma-ray telescopes enable the detection of gamma rays emitted by the short-lived radionuclide aluminum-26.

“These are challenging observations. We can only convincingly detect it in two star-forming regions, and the best data are from the Ophiuchus complex,” he said.

The Ophiuchus cloud complex contains many dense protostellar cores in various stages of star formation and protoplanetary disk development, representing the earliest stages in the formation of a planetary system. 

By combining imaging data in wavelengths ranging from millimeters to gamma rays, the researchers were able to visualize a flow of aluminum-26 from the nearby star cluster toward the Ophiuchus star-forming region.

“The enrichment process we’re seeing in Ophiuchus is consistent with what happened during the formation of the solar system 5 billion years ago,” Forbes said. “Once we saw this nice example of how the process might happen, we set about trying to model the nearby star cluster that produced the radionuclides we see today in gamma rays.”

Forbes developed a model that accounts for every massive star that could have existed in this region, including its mass, age, and probability of exploding as a supernova, and incorporates the potential yields of aluminum-26 from stellar winds and supernovas. The model enabled him to determine the probabilities of different scenarios for the production of the aluminum-26 observed today.

“We now have enough information to say that there is a 59 % chance it is due to supernovas and a 68 % chance that it’s from multiple sources and not just one supernova,” Forbes said.

Multi-wavelength astronomy gives different data for the same area in the sky (ESA)

The new findings also show that the amount of short-lived radionuclides incorporated into newly forming star systems can vary widely. “Many new star systems will be born with aluminum-26 abundances in line with our solar system, but the variation is huge—several orders of magnitude,” Forbes said. 

“This matters for the early evolution of planetary systems, since aluminum-26 is the main early heating source. More aluminum-26 probably means drier planets.”

The study researchers hope that these results will help achieve a more accurate understanding of the deep history of the solar system, which may help in the future to understand the degree of its uniqueness compared to the vast cosmic ocean.