![]() ![]() Therefore elemental and isotopic abundance ratios can provide information on the age of a system and have often been used as a cosmic clock. The element abundances and the isotopic ratios depend on the mass of the star. 1 Introductionĭuring the life of a galaxy, different elements are produced inside stars of different masses and different lifetimes. Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. They suggest that the effect of super-asymptotic giant branch stars or fast-rotating massive stars was significant in the early Galaxy. These abundances give information about the early composition of the cloud from which HD 140283 was formed. We also obtained a precise determination of the abundance of the CNO elements in this star. For the first time, we were able to measure the 12C/ 13C ratio in a very old metal-poor dwarf that was born at the very beginning of the Galaxy: 12C/ 13C = 33 −6 +12. We used very high spectral resolution data, with extremely high signal-to-noise ratios obtained with the spectrographs ESPaDOnS at the CFHT, ESPRESSO at the VLT, and HARPS at the ESO 3.6 m telescope. The aim of this work is to measure the precise abundances of carbon, nitrogen, oxygen, and mainly the 12C/ 13C isotopic ratio in this very old metal-poor star in order to have a good reference for the computations of the chemical evolution of the Galaxy. It is very old, and the chemical abundance in this star is a good witness of the chemical composition of the matter in the early Galaxy.Īims. ![]() ![]() The star HD 140283 is one of the best-studied very metal-poor dwarf stars. The isotope abundances provide powerful diagnostics of the chemical enrichment in our Galaxy. GEPI, Observatoire de Paris, PSL Research University, CNRS, Place Jules Janssen,Į-mail: de São Paulo, IAG, Rua do Matão 1226, Cidade Universitária,Ĭontext. Astronomical objects: linking to databases.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes ![]()
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