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 ?
The study found coexistence of native metallicity and ferroelectricity in bulk crystalline tungsten ditelluride (WTe2) at room temperature.
But while many properties of stars are measurable, meaningful helium abundances (y) remain elusive and as a result fundamental properties are not accurate.helium enrichment laws, which underpin most stellar properties, link initial y to initial metallicity, but these relations are very uncertain with gradients (dy/dz) spanning the range 1 to 3.
By figuring out the abundance of different elements within the star, or its metallicity, researchers can now further refine the age of the object, Moss and Kloc reported in two separate AAS poster presentations.
Residing in the same part of the Milky Way galaxy as our own solar system, the star is believed to be up to 13.5 billion years old which is evidenced by its extremely low metal content, or metallicity, Xinhua news agency reported.
M54 has been proposed as the actual nucleus of the galaxy, but a 2008 investigation using velocity and metallicity data concluded M54 formed independently and plunged to its current location at 87,000 light-years distant due to dynamical friction.
"Using the metallicities of the stars in the catalogues from the high quality spectral atlases of APOGEE and LAMOST, and with the distances at which the objects are situated, we have shown that there are an appreciable fraction of stars with higher metallicity, [a] characteristic of disc stars, further out than the previously assumed limit on the radius of the Galaxy disc," study co-author Carlos Allende said in a (https://www.eurekalert.org/pub_releases/2018-06/idad-tdo060718.php) statement.
Another relevant uncertainty concerning the progenitor systems for LGRBs is the role of metallicity Z.
Watauchi et al., "Charge ordering, commensurability, and metallicity in the phase diagram of the layered," Physical Review Letters, vol.
To maintain consistency with existing Solar data, in this work we consider the high metallicity Standard Solar Model (SSM) [21].
Chen, "A scanning probe microscopy based assay for single-walled carbon nanotube metallicity," Nano Letters, vol.
It is seen that the Nyquist plots of the as-synthesized W[O.sub.3] and W[O.sub.2.90] both present a complete semicircle, while those of [W.sub.19][O.sub.55] and [W.sub.18][O.sub.49] only show a trend for a semicircle, possibly because, with increasing x, the semiconductivity of W[O.sub.3-x] decreased and the metallicity increased.
We present a review of the literature and new photometry of the cluster looking specifically at potentially new members of the system and present plans for a spectroscopic campaign to determine metallicity of the cluster.