NGC 6397

The globular cluster NGC 6397 contains around 400,000 stars and is found some 7,200 light years away in the southern constellation Ara. Together with halo stars, globular-cluster stars are among the oldest objects in the Milky Way, and hold the nuclear relics of the Big Bang. Evidence for complex internal hydrodynamic processes that reduce these stars' lithium abundance could explain the cosmological lithium discrepancy, as Korn and colleagues reveal (image and text: Nature 442 657).

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