University of Chicago researchers say a study of meteorites suggests the radioactive isotope iron 60 -- the telltale sign of an exploding star -- is low in abundance and well mixed with solar system material.
This contradicts previous studies that seemed to suggest high amounts of the radioactive isotope in early solar system materials, they said.
Some astronomers have proposed a shock wave from a nearby supernova may have triggered the formation of the sun by causing regions of the dust cloud out of which the solar system formed to collapse and coalesce.
"If you have iron 60 in high abundance in the solar system, that's a 'smoking gun' -- evidence for the presence of a supernova," geophysical sciences Professor Nicolas Dauphas said in a university release.
However, Dauphas and co-researcher Haolan Tang said their analysis gave different results from previous work, suggesting levels of iron 60 were uniform and low in early material.
The duo suggest previous methods of analyzing meteorites kept the samples intact and did not remove impurities sufficiently, which may have led to greater errors in measurement.
Tang and Dauphas suggest the low levels of iron 60 probably came from the long-term accumulation of the isotope in the interstellar medium from the remains countless stars past, instead of a nearby cataclysmic event like a supernova.