Astronomers Couldn't Explain This Ancient Star's Chemistry. A Lab Experiment Just Did.

A new paper published in Nature Communications Physics from a group of researchers led by Caley M. Harris, a graduate student at Michigan State University, has found an answer to why strontium levels in certain ancient stars are skewed. The researchers used a lab experiment at the Californium Rare Isotope Breeder Upgrade facility at Argonne National Laboratory to measure the neutron capture rate of Krypton-88. They used Bromine-89, which decays into Krypton-89, to gain insights into Krypton-88's behavior. The study found that Krypton-88 absorbs neutrons efficiently, which explains why strontium is more common in observed stars than predicted by models. The experiment provided precise measurements of the neutron capture rate, aligning with the observed isotope ratios in CEMP stars. The findings suggest that the intermediate neutron-capture process, previously thought to be incomplete, is actually responsible for the observed strontium levels. The study highlights the importance of experimental validation in astrophysical models and shows how laboratory techniques can solve long-standing mysteries in cosmic nucleosynthesis.

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