We present the first detection of beryllium in two turnoff stars of the old, metal-poor globular cluster NGC 6397. The beryllium lines are clearly detected and we determine a mean beryllium abundance of log(Be/H)= −12.35± 0.2. The beryllium abundance is very similar to that of field stars of similar Fe content. We interpret the beryllium abundance observed as the result of primary spallation of...

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, most recently, via the precision cosmology that has become feasible with the mapping of the acoustic peaks in the cosmic microwave background. We demonstrate that all three met...

Powerful astronomical spectra reveal an urgent need for additional work on atomic lines, levels, and oscillator strengths. The star HD 65949 provides some excellent examples of species rarely identified in stellar spectra. For example, the Re ii spectrum is well developed, with 17 lines between 3731 and 4904 Å, attributed wholly or partially to Re ii. Classifications and oscillator strengths ar...

Powerful astronomical spectra reveal an urgent need for additional work on atomic lines, levels, and oscillator strengths. The star HD 65949 provides some excellent examples of species rarely identified in stellar spectra. For example, the Re ii spectrum is well developed, with 17 lines between 3731 Å and 4904 Å, attributed wholly or partially to Re ii. Classifications and oscillator strengths ...

The Mn–Cr decay system, in which Mn decays to Cr (t1/2 = 3.7 Ma) has been widely used to construct Cr/Cr vs. Mn/Cr isochrons and thus determine relative ages of early solar system objects or events, assuming that the initial Cr isotopic ratio, (Cr/Cr)o, equals ( Mn/Cr)o. With the primary objective of interpretation of these ages within a diffusion kinetic framework, we have determined the trace...

The reliable evaluation of the r-process production of the actinides and careful estimates of the uncertainties affecting these predictions are key ingredients especially in nucleo-cosmochronology studies based on the analysis of very metal-poor stars or on the composition of meteorites. This type of information is also required in order to make the best possible use of future high precision da...

Context. An accurate assessment of white dwarf cooling times is paramount so that white dwarf cosmochronology of Galactic populations can be put on more solid grounds. This issue is particularly relevant in view of the enhanced observational capabilities provided by the next generation of extremely large telescopes, that will offer more avenues to use white dwarfs as probes of Galactic evolutio...