Results 1 to 10 of about 92 (70)

White dwarf cooling sequences and cosmochronology [PDF]

EPJ Web of Conferences, 2013
The evolution of white dwarfs is a simple gravothermal process. This means that their luminosity function, i.e. the number of white dwarfs per unit bolometric magnitude and unit volume as a function of bolometric magnitude, is a monotonically increasing ...
J Isern, E Garcia-Berro
exaly   +4 more sources

Evidence against solar influence on nuclear decay constants. [PDF]

Phys Lett B, 2016
The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 ...
Pommé S, Stroh H, Paepen J, Van Ammel R, Marouli M, Altzitzoglou T, Hult M, Kossert K, Nähle O, Schrader H, Juget F, Bailat C, Nedjadi Y, Bochud F, Buchillier T, Michotte C, Courte S, van Rooy MW, van Staden MJ, Lubbe J, Simpson BR, Fazio A, De Felice P, Jackson TW, Van Wyngaardt WM, Reinhard MI, Golya J, Bourke S, Roy T, Galea R, Keightley JD, Ferreira KM, Collins SM, Ceccatelli A, Unterweger M, Fitzgerald R, Bergeron DE, Pibida L, Verheyen L, Bruggeman M, Vodenik B, Korun M, Chisté V, Amiot MN.   +43 more
europepmc   +2 more sources

Toward precision cosmochronology [PDF]

Astronomy and Astrophysics, 2020
The continuous cooling of a white dwarf is punctuated by events that affect its cooling rate. The most significant of these events is the crystallization of its core, a phase transition that occurs once the C/O interior has cooled down below a critical temperature.
Simon Blouin, Jérôme Daligault, D Saumon   +2 more
exaly   +3 more sources

Nuclear cosmochronology

Annals of Physics, 1960
In the studies described in this paper we make quantitative use of the radio-active decays of uranium and thorium in cosmochronology in much the same manner as these decays have been employed in geochronology. The paper is divided into two quite different parts representing different views as to the immediate source of the material that now constitutes
William A Fowler
exaly   +4 more sources

WHITE DWARF COSMOCHRONOLOGY IN THE SOLAR NEIGHBORHOOD [PDF]

Astrophysical Journal, 2014
The study of the stellar formation history in the solar neighborhood is a powerful technique to recover information about the early stages and evolution of the Milky Way. We present a new method which consists of directly probing the formation history from the nearby stellar remnants.
P -E Tremblay, J S Kalirai, M Cignoni
exaly   +4 more sources

INHOMOGENEITIES OF CHEMICAL COMPOSITION AND COSMOCHRONOLOGY PROBLEMS

Odessa Astronomical Publications, 2017
The problems of determination of chemical composition of stars and connection with theory of chemical evolution of Galaxy are discussed.
V. G. Klochkova, V. E. Panchuk
doaj   +3 more sources

A nuclear correction factor for Re/Os cosmochronology

Astrophysical Journal, 1979
Modification of the laboratory cross sections for neutron capture on /sup 186/Os and /sup 187/Os caused by the excitation of these target nuclei to a thermal distribution of low-lying nuclear excited states is examined for temperatures appropriate to the stellar s-process (near 30 keV).
W A Fowler
exaly   +2 more sources

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 ...
E Biémont, P Palmeri, P Quinet
exaly   +4 more sources

Correlation Between U/Th and Pb/Os Abundance Ratios and its Application in Nuclear Cosmochronology

Astrophysical Journal
The abundance ratios of radioactive elements U/Th and stable elements Pb/Os from the r -process are found to have a strong correlation. This correlation is quite robust with respect to astrophysical conditions.
S Q Zhang
exaly   +2 more sources

Beryllium in turnoff stars of NGC 6397: Early Galaxy spallation, cosmochronology and cluster formation [PDF]

Astronomy and Astrophysics, 2004
We present the first detection of beryllium in two turnoff stars of the old, metal-poor globular cluster NGC 6397. The beryllium lines are clearly detected and we determine a mean beryllium abundance of log(Be/H)=-12.35 +/- 0.2. The beryllium abundance is very similar to that of field stars of similar Fe content.
L Pasquini, P Bonifacio, S Randich
exaly   +3 more sources