HE0107-5240 is a star in more than one sense of the word. Chemically, it is the most primitive object yet discovered, and it is at the centre of debate about the origins of the first elements in the Universe. Late last year, the discovery of the most iron-deficient star yet identified, HE0107-5240, was announced. This star has a measured abundance of iron less than 1/200,000 that of the Sun. Its significance is that it seems to be a relic from the early Universe, and astronomers are now busy considering howto interpret it. In this issue, three groups―Bonifacio et al., Umeda and Nomoto, and Schneider et al.―present various interpretations of HE0107 - 5240. Each of these contributions centres on whether this star exhibits properties that might reveal the likely range of mass that should be associated with the so-called population Ⅲ stars―objects that are presumed to have formed shortly after the Big Bang, and which are thought to have produced the first elements heavier than H, He and Li, as well as the 'first light' in the Universe. Population Ⅱ stars are objects that formed after population Ⅲ stars, and which incorporated the metals created by this previous generation. Our Sun, and other (younger) metal-rich stars in the Galactic disk, are referred to as population Ⅰ objects.
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