منابع مشابه
Solar System Abundances and Condensation Temperatures of the Elements
Solar photospheric and meteoritic CI chondrite abundance determinations for all elements are summarized and the best currently available photospheric abundances are selected. The meteoritic and solar abundances of a few elements (e.g., noble gases, beryllium, boron, phosphorous, sulfur) are discussed in detail. The photospheric abundances give mass fractions of hydrogen (X 1⁄4 0:7491), helium (...
متن کاملPhotochemical modeling of CH3 abundances in the outer solar system
Recent measurements of methyl radicals (CH3) in the upper atmospheres of Saturn and Neptune by the Infrared Space Observatory (ISO) provide new constraints o photochemical models of hydrocarbon chemistry in the outer solar system. The derived column abundances of CH3 on Saturn above 10 mbar and Neptune above the 0.2 mbar t3 -2 ß pressure level are (2.5 6.0) x 1013 cm -2 and (0.7 2.8) x 10 cm , ...
متن کاملSolar Abundances of the Elements
The isotopic compositions of noble gases in the solar wind show high enrichments of light isotopes. When corrected for mass fractionation all five noble gases there can be resolved in terms of the two primitive noble gas components that have been identified in planetary solids. Reasons are presented for assigning the fractionation to a solar process that selectively enriches lighter nuclei at t...
متن کاملHelioseismology and Solar Abundances
Helioseismology has allowed us to study the structure of the Sun in unprecedented detail. One of the triumphs of the theory of stellar evolution was that helioseismic studies had shown that the structure of solar models is very similar to that of the Sun. However, this agreement has been spoiled by recent revisions of the solar heavy-element abundances. Heavy element abundances determine the op...
متن کاملMeasuring Solar Abundances with Seismology
The revision of the photospheric abundances proferred by Asplund et al has rendered opacity theory inconsistent with the seismologically determined opacity through the Sun. This highlights the need for a direct seismological measurement of solar abundances. Here we describe the technique used to measure abundances with seismology, examine our ability to detect differences between solar models u...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1991
ISSN: 0074-1809
DOI: 10.1017/s0074180900227265