1) The relative amount of a given → chemical element
with respect to other elements.
M.E., from O.Fr. abundance, from L. abundantia "fullness," from abundare "to overflow," from L. → ab- "away" + undare "to surge," from unda "water, wave."
Farâvâni "abundance," from farâvân "abundant," from feré "much, more; increase; priority;" Mid.Pers. frêh "more, much;" O.Pers. fra- "before, forth;" Av. frā, fərrā "forth, forward;" PIE base *pro-; cf. L. pro "on behalf of, in place of, before, for;" Gk. pro- "before, in front of."
farâvâni-ye šimiyâyi (#)
Fr.: abondance chimique
The relative amount of a given → chemical element or → chemical compound with respect to another element or compound in a given sample.
Fr.: abondance de deutérium
The number of → deuterium (D) atoms with respect to
→ hydrogen (H) in an astrophysical object.
Deuterium is a primordial product of → Big Bang nucleosynthesis.
According to theoretical models, the primordial D/H ratio is estimated to be
(2.61 ± 0.15) x 10-5 (Steigman et al. 2007, MNRAS 378, 576).
Nuclear reactions in stars convert D into
He tending to a lower D/H ratio in the → interstellar medium
over time (→ deuterium burning).
However, chemical and physical → fractionation
processes can produce local → enhancements in the D/H ratio.
For example, low-temperature ion-molecule reactions in
→ molecular cloud cores can enhance
the D/H ratio in icy grains by as much as two orders of magnitude
above that observed in the interstellar medium.
farâvâni-ye bonpâr, ~ onsor
Fr.: abondance élémentaire, ~ d'un élément
Emission nebulae: The relative amount of a given → chemical element in an ionized nebula with respect to another element, usually → hydrogen. Elemental abundance ratios of → emission nebulae are obtained either by adding the observed → ionic abundances of the element or by using → ionization correction factors. Same as → total abundance.
Elemental, from M.L. elementalis, → element + -al; abundance, from O.Fr. abundance, from L. abundantia "fullness," from abundare "to overflow," from L. ab- "away" + undare "to surge," from unda "water, wave;" → abundance.
Fr.: abondance de l'hélium
The relative amount of helium with respect to another → chemical species, usually → hydrogen, in an astronomical object.
Fr.: abondance ionique
A quantity, pertaining to an ion of a chemical element, expressing the relative number of the ion with respect to that of hydrogen.
farâvâni-ye šaxâne-yi, ~ šahânsangi
Fr.: abondance météoritique
The abundance of a chemical element as derived from meteorites. Meteoritic abundances measured from carbonaceous → CI chondrites are believed to represent → protosolar abundances.
→ meteoritic; → abundance.
The abundance of a chemical element exceeding a reference value, in particular compared to that of the Sun.
Fr.: abondance primordiale
The relative amount of a light element (e.g. deuterium, lithium, helium) synthesized in the early Universe.
→ primordial; → abundance.
Fr.: abondance protosolaire
The abundance of a chemical element pertaining to the proto-→ solar nebula from which the → solar system was formed. → CI chondrite; → CAI meteorite.
→ protosolar; → abundance.
Fr.: abondance solaire
→ solar photospheric abundance, → solar system abundance.
solar photospheric abundance
farâvâni-ye šidsepehri-ye xoršidi
Fr.: abondance photosphérique solaire
The abundance of a → chemical element as determined from the observation of solar → spectral lines. The solar chemical composition is an important ingredient in our understanding of the formation, structure and evolution of both the Sun and our solar system. Furthermore, it is an essential reference standard against which the elemental contents of other astronomical objects are compared (Asplund et al. 2009, arXiv:0909.0948). The photospheric abundances relative to hydrogen are not representative of the → protosun, or global → solar system abundances. This is because heavy-element fractionation in the Sun has altered photospheric abundances (Lodders 2003, ApJ 591, 1220).
→ solar; → photospheric; → abundance.
solar system abundance
farâvâni-ye râžmân-e xoršidi
Fr.: abondance dans le système solaire
Same as → protosolar abundance.
→ solar system; → abundance.
Fr.: abondance totale
Same as → elemental abundance.
The abundance of a chemical element being lower than a reference value, in particular compared to that of the Sun.