Calcium solar abundance

Fig. 3.42. Depletion below solar abundances of elements in the H I gas towards f Ophiuchi plotted against atomic mass number in (a) and condensation temperature in (b), based in part on the curve of growth shown in Fig. 3.11. Vertical boxes indicate error bars. The dotted curve in the left panel represents an A-1/2 dependence expected for non-equilibrium accretion of gas on to grains in the ISM. The condensation temperature gives a somewhat better, though not perfect, fit, suggesting condensation under near-equilibrium conditions at a variety of temperatures either in stellar ejecta or in some nebular environment. Note the extreme depletion of Ca ( Calcium in the plane stays mainly in the grain ). After Spitzer and Jenkins (1975). Copyright by Annual Reviews, Inc.

Natural isotopes of calcium and their solar abundances... 

We present here the results of abundance measurements of iron, calcium and nickel in four open clusters, from UVES spectra of solar type stars. A code developed by one of the authors (Francois) performs line recognization, equivalent width measurements and finally obtains the abundances by means of OSMARCS LTE model atmosphere [4]. Temperature, gravity and microturbulence velocity have to be input to the program. This is made in an automatic way for a grid of values chosen on photometric basis. Those that best reproduce excitation and ionization equilibria are selected and used, namely when no significant trend of the computed abundances is seen, neither versus the excitation potential of the line nor versus its equivalent width, and for which the abundances obtained with lines of different ionization stages of the same specie give equal results within the errors. This check is made with iron lines, we have in fact at least thirty Fe I lines in each star, and six Fell lines. 

Even nuclei, and in particular the class of a nuclei (oxygen, magnesium, silicon, calcium), are the basic products of nucleosynthesis in high-mass stars. They are abundantly present in the ashes of SNll events, where the cx/iron ratio is about three times the solar value. The amounts of even elements ejected by explosion of a high-mass star are, to the first approximation, independent of the star s initial metallicity. 

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. 

Calcium-41 decays to 4XK with a half-life of 1.03 x 105 yr (A, = 6.73 x 10-6yr-1). Calcium is a refractory alkaline earth element, while potassium is a moderately volatile alkaline element. Thus, calcium and potassium can be separated by both chemical and thermal processes. The short half-life of 41Ca means that the abundance in the early solar system was very low. Therefore, minerals with very high Ca/K ratios are required in order for the... 

It is but the 64th most abundant isotope in the solar system, comparable to minor calcium isotopes or to 7Li, the most abundant Big-Bang product outside ofH and He. 

From the isotopic decomposition of normal calcium one finds that the mass-43 isotope, 43Ca, is second least abundant of the stable Ca isotopes 0.135% °f all calcium. On the scale where one million silicon atoms is taken as the standard for solar-system matter, this isotope has... 

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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