Stars with the chemical clock on hold

Astrophysicists have 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 of the Galactic disc is more complex than originally assumed.