Chromium solar abundance

SNII events alone explain the observed solar abundance distribution between oxygen and chromium. This can be taken as a major theoretical achievement. Complementary sources of hydrogen, helium, lithium, beryllium, boron, carbon and nitrogen are required, and these have been identified. They are the Big Bang, cosmic rays and intermediate-mass stars. Around iron and a little beyond, we must invoke a contribution from type la supernovas (Pig. 8.5). These must be included to reproduce the evolution of iron abundances, a fact which suggests... 

Natural isotopes of chromium and their solar abundances... 

Among the elements that make up rocks and minerals, silicon, magnesium, and iron are of almost equal abundance followed by sulfur, aluminum, calcium, sodium, nickel, and chromium. Two of the most common minerals in meteorites and in the terrestrial planets are olivine ((Mg,Fe)2Si04) and pyroxene ((Mg,Fe,Ca)Si03). The composition obtained by averaging these two minerals is very similar to the bulk solar system composition, so it is really no surprise that they are so abundant. 

Direct measurements of the initial abundance of 53Mn in the early solar system have proven unreliable. CAIs, the first solids to form in the early solar system, are highly depleted in both manganese and chromium, both of which are moderately volatile. Operationally, the relative 53Mn-53Cr timescale has been anchored to an angrite, LEW 86010 (see above). Age differences have been calculated relative to LEW 86010 from... 

From the isotopic decomposition of normal chromium one finds that the mass-50 isotope, 5°Cr, is the second least abundant of all the Cr isotopes 4.35% of all Cr. Using the total abundance of elemental Cr = 1.35 x lo4 per million silicon atoms in solar-system matter, this isotope has... 

The sun is not a "perfect" radiator, nor does it have uniform composition. The sun is composed of about 92% hydrogen, 7.8% helium. The remaining 0.2% of the sun is made up of about 60 other elements, mainly metals such as iron, magnesium, and chromium. Carbon, silicon, and most other elements are present as well.1 The inte raction of the atoms and ions of these elements with the radiation created by the annihilation of matter deep within the sun modifies and adds structure to the solar spectral distribution of energy. Astrophysicists such as Kurucz have used quantum calculations and the relative abundance of elements in the sun to compute the theo retical spectral distribution from first principles.5 Figure 1 shows a plot of the Kurucz computed spectral distribution at very high resolution (0.005 nanometer at UV) as well as an inset showing much lower resolution (0.5 nanometer in UV to 5 nm in IR) plot. 

Based on the bulk chemistry, IDPs are divided into two groups (i) micrometer-sized chondritic particles and (ii) micrometer-sized nonchondritic particles. A particle is defined as chondritic when magnesium, aluminum, silicon, sulfur, calcium, titanium, chromium, manganese, iron, and nickel occur in relative proportions similar (within a factor of 2) to their solar element abundances, as represented by the Cl carbonaceous chondrite composition (Brownlee et al., 1976). Chondritic IDPs differ significantly in form and texture from the components of known carbonaceous chondrite groups and are highly enriched in carbon relative to the most carbon-rich Cl carbonaceous chondrites (Rietmeijer, 1992 Thomas et al., 1996 Rietmeijer, 1998, 2002). 

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