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 ?
Moreover, the stars that formed from the metal-poor gas would be metal-poor themselves.
Massive galaxies tend to have both metal-poor (appearing blue) and metal-rich (appearing red) globular clusters.
Giant galaxies like the NGC 1277 generally contain both metal-rich (red in appearance) and metal-poor (blue in appearance) globular clusters.
We will determine the metallicity effect on Cepheid luminosities by a) determining a 2% distance to the more metal-poor SMC with our binary method, and by b) measuring the distances to LMC and SMC with an improved Baade-Wesselink (BW) method.
They include discussion of heliosphere boundary measurements, interstellar grain alignments, molecular gas, stars, star formation, planetary physics, exoplanetary systems, high-velocity stars, metal-poor stars, galactic archaeology, semianalytic vs.
The astronomers concluded that the best explanation for the unusual properties of GRB 130925A was that it heralded the death of a metal-poor blue supergiant, a model they suggested likely characterizes the entire ultra-long class.
Title: HST Observations of Globular Clusters and Metal-Poor Stars
Stars with a lower fraction of heavy elements are considered metal-poor.
Among the topics are the evolution and nucleo-synthesis of extremely metal-poor AGB stars, the second release of the Torun Catalogue of galactic post-AGB stars, double chemistry in galactic bulge planetary nebulae, and the role of AGB stars in the global gas and dust budget of the Large Magellanic cloud.
In addition, 18 papers reported research results in such areas as the dark matter halo shape of NGC 2976 via stellar kinematics, investigating inner disk lifetimes in Ophiuchus, barred galaxies in the Coma Cluster, and detailed abundances in a metal-poor stellar stream.
Beers observes that the existence of small, metal-poor stars in the outer halo suggests a new story of the evolution of the galaxy.
Yet the little galaxy has certainly been around a long time, because Hubble has detected in it RR Lyrae stars, metal-poor pulsators that are more than 10 billion years old.

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