Nucleocosmochronology or nuclear cosmochronology is a technique used to determine timescales for
astrophysical
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...
objects and events. It compares the observed ratios of
abundances of heavy
radioactive
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...
and
stable nuclide
Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes.
Th ...
s to the primordial ratios predicted by
nucleosynthesis
Nucleosynthesis is the process that creates new atomic nuclei from pre-existing nucleons (protons and neutrons) and nuclei. According to current theories, the first nuclei were formed a few minutes after the Big Bang, through nuclear reactions in ...
theory in order to calculate the age of formation of astronomical objects.
Nucleocosmochronology has been employed to determine the age of the
Sun
The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
( billion years) and of the Galactic
thin disk
The thin disk is a structural component of spiral and S0-type galaxies, composed of stars, gas and dust. It is the main non-centre (e.g. galactic bulge) density, of such matter. That of the Milky Way is thought to have a scale height of around ...
( billion years),
del Peloso et al., "The age of the Galactic thin disk from Th/Eu nucleocosmochronology III. Extended sample." ''Astronomy & Astrophysics'', 440, (2005) 1153.
/ref> among others. It has also been used to estimate the age of the Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
itself, as exemplified by a recent study of Cayrel's Star
BPS CS31082-0001, named Cayrel's Star , is an old Population II star located in a distance of 2.1 kpc in the galactic halo. It belongs to the class of ultra-metal-poor stars (metallicity Fe/Hydrogen.html"_;"title="Iron.html"_;"title= ...
in the Galactic halo
A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component. Several distinct components of galaxies comprise the halo:
* the stellar halo
* the galactic corona (hot gas, i.e. a plas ...
, which due to its low metallicity, is believed to have formed early in the history of the Galaxy. Limiting factors in its precision are the quality of observations of faint stars and the uncertainty of the primordial abundances of r-process elements.
See also
* Astrochemistry
Astrochemistry is the study of the abundance and reactions of molecules in the Universe, and their interaction with radiation. The discipline is an overlap of astronomy and chemistry. The word "astrochemistry" may be applied to both the Solar Syst ...
* Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves. Absolute geochronology can be accomplished through radioactive isotopes, whereas relative geochronology is ...
* Gyrochronology
References
Dating methods
Astrophysics
Nuclear physics
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