Related papers: Galactic evolution of D, 3He and 4He
Recent observations of 3He/H in different environments tend to prove that 3He is not produced in low mass stars, contrary to the standard predictions of stellar evolution theory. We show how a simple consistent mechanism, namely…
Quasar absorption lines now permit a direct probe of deuterium abundances in primordial material, with the best current estimate $ (D/H)=1.9\pm 0.4 \times 10^{-4}$. If this is the universal primordial abundance $(D/H)_p$, Standard Big Bang…
Current measurements indicate that the deuterium abundance in diffuse interstellar gas varies spatially by a factor of ~4 among sightlines extending beyond the Local Bubble. One plausible explanation for the scatter is the variable…
Estimates of the deuterium abundance in quasar absorbers are reviewed, including a brief account of incorrect claims published by the author and a brief review of the problem of hydrogen contamination. It is concluded that the primordial…
Of all the light elements, lithium is the most sensitive indicator of stellar evolution. This review discusses current data on the abundance of lithium in the atmospheres of A-, F-, G-, and K-stars of different types, as well as the…
We examine galactic chemical evolution models which reproduce the present-day and pre-solar values of deuterium starting with a primordial value which is consistent with a baryon-to-photon ratio of $3 \times 10^{-10}$. We consider various…
During the era of primordial nucleosynthesis the light elements 2H, 3He, 4He, and 7Li were produced in significant amounts and these abundances have since been modified primarily by stars. Observations of 3He+ in HII regions located…
Sulphur is an important, volatile alpha element but its role in the Galactic chemical evolution is still uncertain. We derive the S abundances in RGB stars in three Galactic globular clusters (GC) that cover a wide metallicity range…
The dust abundance of the interstellar medium plays an important role in galaxy physics, the chemical evolution of matter and the absorption and re-emission of stellar light. The last years have seen a surge in observational and theoretical…
Chemical abundances provide important clues to the evolution of galaxies. Ionized nebulae are one of the main sources of chemical abundance measurements, especially in external galaxies. Studies of H II regions have shown that the overall…
Deuterons are the most abundant secondary cosmic ray species in the Galaxy, but their study has been severely limited due to experimental challenges. In an era with new experiments and high-precision measurements in cosmic rays, having a…
We discuss the chemical evolution of dwarf irregular and blue compact galaxies in light of recent data, new stellar yields and chemical evolution models. We examine the abundance data for evidence of HII region self-enrichment effects,…
The evolution of the 7Li abundance in the Galaxy has been computed by taking into account several 7Li sources: novae, massive AGB stars, C-stars, Type II SNe and GCRs. The theoretical predictions for the evolution of the 7Li abundance in…
A new observation of D in a primordial gas cloud, made using the high resolution spectrograph at the Keck telescope, indicates an abundance $ D/H =(1.9-2.5) \times 10^{-4}$ \cite{SCHR}. Since deuterium is destroyed by stars, and the…
As the Galaxy evolves, the abundance of deuterium in the interstellar medium (ISM) decreases from its primordial value: deuterium is "astrated". The deuterium astration factor, f_D, the ratio of the primordial D abundance (the D to H ratio…
After a short historical (and highly subjective) introduction to the field, I discuss our current understanding of the origin and evolution of the light nuclides D, He-3, He-4, Li-6, Li-7, Be-9, B-10 and B-11. Despite considerable…
A prediction of standard inflationary cosmology is that the elemental composition of the medium out of which the earliest stars and galaxies condensed consisted primarily of hydrogen and helium 4He with small admixtures of deuterium,…
The light elements D, \he3, \he4, and \li7 are produced in big bang nucleosynthesis and undergo changes in their abundances due to galactic processing. Since one may observe most of these elements only in contemporary environments,…
Status quo and perspectives of standard chemical evolution models of Local Group galaxies are summarized, discussing what we have learnt from them, what we know we have not learnt yet, and what I think we will learn in the near future. It…
The comparison of cosmic abundances of the light elements with the density of baryonic stars and gas in the universe today provides a critical test of big bang theory and a powerful probe of the nature of dark matter. A new technique allows…