Related papers: Light Elements in Main Sequence Stars: Li, Be, B, …
Understanding the formation of the first stars and galaxies is a key problem in modern cosmology. In these lecture notes, we will derive some of the basic physical principles underlying this emerging field. We will consider the basic…
We present new Hubble Space Telescope (HST) abundance observations of the neutron-capture elements Ge, Zr, Os and Pt in a group of 11 Galactic halo stars, including the well studied r-process rich CS 22892-052 and the r-process poor, bright…
Methods to determine abundances of the elements in the atmospheres of F, G, and K stars with precisions of 0.01-0.03 dex are reviewed. Such high-precision stellar abundances have led to the discovery of unexpected phenomena and relations…
Radial abundance gradients are observed in the Galaxy and other galaxies as well, and include several chemical elements in different stellar systems. Possibly the most accurate gradients in the Galaxy are those determined from chepheid…
We present an abundance analysis of six main sequence turnoff, subgiant, and giant branch stars toward the Galactic bulge that were observed with Keck/HIRES during microlensing events. This is an early look at the first detailed chemical…
A chemical study of normal Galactic C(N) carbon stars is presented. Abundances of Li, CNO isotopes and s-elements are derived. The derived abundances of s-elements nicely agree with theoretical s-process nucleosynthesis predictions during…
During its hot, dense, early evolution the Universe was a primordial nuclear reactor, synthesizing the light nuclides D, 3He, 4He and 7Li in the first thousand seconds. The presently observed abundances of these relic nuclides provide a…
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…
There is compelling observational evidence that globular clusters (GCs) are quite complex objects. A growing body of photometric results indicate that the evolutionary sequences are not simply isochrones in the observational plane -as…
The oldest stars in the universe retain to a great extent detailed information on the chemical composition of the interstellar medium at the time of their birth. Hence the earliest phases of Galactic chemical evolution and nucleosynthesis…
The cosmic microwave background and the cosmic expansion can be interpreted as evidence that the Universe underwent an extremely hot and dense phase about 14 Gyr ago. The nucleosynthesis computations tell us that the Universe emerged from…
Chemical abundances of stars in the Milky Way disk are empirical tracers of its enrichment history. However, they capture joint-information that is valuable to disentangle. In this work, we seek to quantify how individual abundances evolve…
Be abundances of old, low metallicity halo stars have major implications on cosmic-ray origin, requiring acceleration out of fresh supernova ejecta. The observed, essentially constant Be/Fe fixes the Be production per SNII, allowing the…
Big Bang nucleosynthesis produces only light elements and the very first generation stars are thus formed from metal-free clouds. They start the production of heavy elements during their life, and enrich the interstellar medium through…
In a large scale view of the universe, galaxies are the basic unit of structure. A typical bright galaxy may contain 100 billion stars and span tens of thousands of light years, but the empty expanses between the galaxies are much larger…
We present an analysis of eight star-forming galaxies with $\langle z \rangle = 4.0$ from the JWST EXCELS survey for which we obtain robust chemical abundance estimates for the $\alpha$-elements O, Ne and Ar. The $\alpha$-elements are…
Previous work on the abundances of C, O, Na, Mg, Si, Ca, Ti, Cr, Mn, Fe, Ni, Cu, and Zn in low-alpha (accreted) and high-alpha (in situ born) halo stars is extended to include the abundances of Sc, V, and Co, enabling us to study the…
Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations demonstrate that the earliest generations of stars in the Galaxy,…
We reconsider the effects of unstable particles on the production and destruction of the primordial light elements, with a view to reconciling the high primordial Li7 abundance deduced from Big Bang Nucleosynthesis (BBN), as implied by the…
For a brief time in its early evolution the Universe was a cosmic nuclear reactor. The expansion and cooling of the Universe limited this epoch to the first few minutes, allowing time for the synthesis in astrophysically interesting…