Witnessed by the starlight: A meteorite offering insight into the solar system's origins

In a groundbreaking study, researchers from Washington University in St. Louis have determined that the ultraviolet light that played a significant role in the formation of our solar system likely came from a long-dead massive star.

The study, led by Lionel Vacher and published in the journal Geochimica et Cosmochimica Acta, suggests that our own solar system was close enough to be affected by the light of massive stars, but not too close to be torn apart. A nearby massive star in the night sky would have appeared brighter than the full moon.

The findings are based on a piece of an asteroid named Acfer 094, found as a meteorite in Algeria in 1990. Acfer 094 is one of the most primitive meteorites in the collection, containing porous regions and tiny grains that formed around other stars.

The sulfur isotope measurements of cosmic symplectite, an intergrowth of iron-oxide and iron-sulfide with extremely heavy oxygen isotopes, found in Acfer 094 were consistent with ultraviolet irradiation from a massive star. However, they did not fit the UV spectrum from the young sun.

The difference in oxygen isotopes between the sun and other planets in the solar system, a difference that was confirmed in 2011, can be explained by a hefty dose of ultraviolet light early in the solar system's history.

The researchers used two in-situ secondary-ion mass spectrometers: NanoSIMS in the physics department and the 7f-GEO in the Department of Earth and Planetary Sciences, for high-precision in-situ sulfur isotope measurements.

The study provides a unique perspective on the astrophysical environment of the sun's birth 4.6 billion years ago. It found evidence of a similar origin story in nascent planetary systems, called proplyds, in the Orion nebula that are being photoevaporated by ultraviolet light from nearby massive O and B stars.

Two theories emerged on the source of the ultraviolet light: either from the young sun or a large nearby star. The study's results lean towards the latter, suggesting that neighboring massive stars were likely close enough that their light affected the solar system's formation.

However, the massive star that likely caused the ultraviolet radiation leading to the split in the local cosmos and influenced the formation of the Sun and the Solar System is not definitively named in the provided search results. Commonly discussed candidates in scientific literature include massive stars in the solar neighborhood that exploded as supernovae before the Sun formed.

The study was published in the journal Geochimica et Cosmochimica Acta with the DOI 10.1016/j.gca.2021.06.026. David Fike, professor of earth and planetary sciences, and Clive Jones, research scientist in earth and planetary sciences, collaborated on the project.

This research offers a fascinating glimpse into the early days of our solar system and the astrophysical environment that shaped its formation. As we continue to unravel the mysteries of the universe, studies like this one bring us one step closer to understanding our cosmic origins.