metallicity

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metallicity

(met-ă-liss -ă-tee) (metal abundance) Symbol: Z . The fraction by mass of metals in a star, cluster of stars, or in some other astronomical entity. Since metals are produced by nucleosynthesis in stars, the metallicity of an object or class of objects depends on when it was formed: objects of later origin in general have a higher metallicity. Metallicity is determined by photometry or high-resolution spectroscopy, and is usually expressed relative to solar metallicity (see cosmic abundance), and as the ratio of iron to hydrogen, Fe/H. See also population I, population II.
References in periodicals archive ?
Researchers suspect that Population III stars are incredibly large, possibly up to a thousand times as massive as the sun.
Scientist Luigi Piro, the director of research at the Institute for Space Astrophysics said that one of the great challenges of modern astrophysics has been the quest to identify the first generation of stars to form in the universe, which they refer to as Population III stars.
The book concludes with the wider cosmological implications, including Population III stars, Lyman break galaxies, and gamma-ray bursts, for each of which massive stars are believed to play a crucial role.
Standard Population III stars were hotter and bluer by comparison," says Freese.
The most massive of these so-called Population III stars would have lived extremely short lives.
Theorists expect Population III stars (as the very first ones are called) to be massive and hot, and thus to shine mostly in ultraviolet light.
Themselves bereft of metals, Population III stars must have evolved in ways that are very different from those seen today, and they may have shaped the early universe in still mysterious ways.
These so-called Population III stars would have contained several hundred solar masses, on average.
The most likely suspects are the so-called Population III stars, the long-hypothesized first stellar generation.
ASTRONOMERS ARE ONE STEP CLOSER TO identifying the first stars born after the Big Bang--the elusive Population III stars.

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