Results 81 to 90 of about 307 (107)
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Subcommission on Geochronology: Convention on the Use of Decay Constants in Geo- and Cosmochronology
Earth and Planetary Science Letters, 1977On August 24, 1976 the IUGS Subcommission on Geochronology (FOOTNOTE 4) met in Sydney, Australia, during the 25th International Geological Congress. They unanimously agreed to recommend the adoption of a standard set of decay constants and isotopic abundances in isotope geology.
E Jäger
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Doubly Ionized Thorium: Laser Lifetime Measurements and Transition Probability Determination of Interest in Cosmochronology [PDF]
Astrophysical Journal, 2002 The first lifetime measurements have been performed for six levels of doubly ionized thorium, an important cosmochronometer in astrophysics for estimating the age of the Galaxy. The levels, belonging to the 5f2, 5f7p, 7s7p, and 6d7p configurations of Th III, have been measured by the time-resolved laser-induced fluorescence method and compared with ...
Patrick Palmeri +2 more
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Cosmochronology with the87Rb/87Sr isobaric pair
Astrophysics and Space Science, 1984The long-lived cosmochronometer87Rb (T 1/2=4.8×1010 yr) is studied. As its origin is partly due tos- and partly tor-process nucleosynthesis it can provide information about the time histories of these processes. The methods of using87Rb quantitatively for a chronological analysis are described. Tentative calculations based on existing experimental data
H. Beer, G. Walter
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Ages from Nuclear Cosmochronology
1986The long-lived radio nuclides 187Re, 232Th, 238U, 235U, and 244Pu can be used to set limits on the galactic age. The interpretation depends on (1) the production ratios of these isotopes in the appropriate nucleosynthesis site, (2) the time-dependent nucleosynthesis rate during galactic evolution, and (3) the isotopic ratios in the matter which ...
F.-K. Thielemann, J. W. Truran
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The Spectral Evolution of Convective Mixing White Dwarfs, the Non-DA Gap, and White Dwarf Cosmochronology [PDF]
Astrophysical Journal Letters, 2012 Submitted to ApJL on Feb. 20, 2012.
Bradley M S Hansen
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Testing White Dwarf Cosmochronology Using Wide Double White Dwarfs
Proceedings of the International Astronomical Union, 2019AbstractWe present a sample of nearly 650 widely separated double white dwarf binaries found using Gaia DR2 astrometry. We derive preliminary total ages for each white dwarf in our sample using Gaia photometry and compare the total ages of both components of each binary in our sample.
Tyler Heintz
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International Meeting for Geochronology, Cosmochronology and Isotope Geology
Geochimica Et Cosmochimica Acta, 1974exaly +2 more sources
White dwarf cosmochronology and M4
2004We discuss the accuracy of the present theoretical models of white dwarfs (WDs). We find that for ages higher than about 6-7 Gyr, the uncertainty in the predicted cooling times is of the order of 25%. The bulk of this uncertainty is due to the chemical profile in the Carbon/Oxygen core and the treatment of the conductive opacity. As a first application
PRADA MORONI, PIER GIORGIO +4 more
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On The β-Decay of 187 Re: An Interface of Atomic And Nuclear Physics And of Cosmochronology
1989Publisher Summary This chapter discusses how a study of the ratios of various isotopes of Re and Os combined with a knowledge of the half-life T 1/2 of the β decay of 187 Re can be helpful in estimating the age of our galaxy. The chapter defines or expands on astrophysical terminology and concepts and which emphasizes the broad view of the ...
Zonghua Chen +2 more
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