Related papers: High-precision nuclear chronometer for the cosmos
Recent observations of r-nuclei, and in particular of Th, in ultra-metal poor stars revived the old idea that the Th cosmochronometry could provide an age estimate of the oldest stars in the Galaxy, and therefore a lower limit to the age of…
The productions of thorium and uranium are key ingredients in $r$-process nucleo-cosmochronology. With the combination of improved nuclear and stellar data, we have made detailed investigations on the $r$-process abundance pattern in the…
The ages of the oldest stars in the Galaxy indicate when star formation began, and provide a minimum age for the Universe. Radioactive dating of meteoritic material and stars relies on comparing the present abundance ratios of radioactive…
Nucleocosmochronology involves the use of the abundances of radioactive nuclear species and their radiogenic decay daughters to establish the finite age of the elements and the time scale for their formation. While there exist radioactive…
Observations of metal-poor Galactic halo stars indicate that the abundance pattern of the (heaviest) neutron-capture elements is consistent with the scaled solar system r-process abundances. Utilizing the radioactive (r-process) element…
Critical views are presented on some nucleo-cosmochronological questions. Progress has been made recently in the development of the 187Re-187Os cosmochronometry. From this, there is good hope for this clock to become of the highest quality…
We obtain age estimates for the progenitor(s) of the extremely metal-poor ([Fe/H = -2.9) halo star CS 31082-001, based on the recently reported first observation of a Uranium abundance in this (or any other) star. Age estimates are derived…
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. The U/Th-Pb/Os correlation…
Abundance ratios of radioactive to stable neutron-capture elements in very metal-poor stars may be used to estimate the age of our Galaxy. But extracting accurate ages from these data requires continuing work on many fronts: a)…
The ages of the oldest stars shed light on the birth, chemical enrichment, and chemical evolution of the Universe. Nucleocosmochronometry provides an avenue to determining the ages of these stars independent from stellar evolution models.…
The long-lived radioactive element thorium can potentially provide a simple and direct clock to determine the age of our Galaxy. Spectroscopic investigations of thorium in metal-poor stars have yielded some promising initial results. We…
The expansion history of the Universe can be constrained in a cosmology-independent way by measuring the differential age evolution of cosmic chronometers. This yields a measurement of the Hubble parameter $H(z)$ as a function of redshift.…
There are three independent techniques for determining the age of the universe: via cosmochronology of long-lived radioactive nuclei, via stellar modelling and population synthesis of the oldest stellar populations, and via the precision…
We review recent observational and theoretical results concerning the presence of actinide nuclei on the surfaces of old halo stars and their use as an age determinant. We present model calculations which show that the observed universality…
The discovery of the second highly $r$-process-enhanced, extremely metal-poor star, CS 31082-001 ([Fe/H] $= -2.9$) has provided a powerful new tool for age determination, by virtue of the detection and measurement of the radioactive species…
A minimum age of the universe can be estimated directly by determining the age of the oldest objects in the our Galaxy. These objects are the metal-poor stars in the halo of the Milky Way. Recent work on nucleochronology finds that the…
The abundance patterns of metal-poor stars provide us a wealth of chemical information about various stages of the chemical evolution of the Galaxy. In particular, these stars allow us to study the formation and evolution of the elements…
The cooling theory of neutron stars is corroborated by its comparison with observations of thermally emitting isolated neutron stars and accreting neutron stars in binary systems. An important ingredient for such an analysis is the age of…
The ages of the oldest stellar objects in our galaxy provide an independent test of the current cosmological model as they give a lower limit to the age of the Universe. Recent accurate parallaxes by the Gaia space mission, accurate…
In practically all known till now methods of nuclear chronometry there were usually taken into account the life-times of only fundamental states of $\alpha$-radioactive nuclei. But in the processes of nuclear synthesis in stars and under…