Stars with the chemical clock on hold

An international team of astrophysicists, led by Cristina Chiappini from the Leibniz Institute for Astrophysics Potsdam, has discovered a group of red giant stars for which the 'chemical clock' does not work: according to their chemical signature, these stars should be old. Instead, they appear to be young when their ages are inferred using asteroseismology. Their existence cannot be explained by standard chemical evolution models of the Milky Way, suggesting that the chemical enrichment history...