With the chemical reaction rate database UMIST95 (Millar etal. 1997) we analyze how uncertainties in rate constants of gas-phase chemical reactions influence the modelling of the molecular abundances in the inter-stellar medium. Random variations are introduced into the rate constants to estimate the scatter in theoretical abundances. Calculations were performed for the dark and translucent mol...

Context. The most recent determination of the solar chemical composition, using a time-dependent, 3D hydrodynamical model of the solar atmosphere, exhibits a significant decrease of C, N, O abundances compared to their previous values. Solar models that use these new abundances are not consistent with helioseismological determinations of the sound speed profile, the surface helium abundance and...

We present the average abundances of the intermediate elements obtained by performing a stacked analysis of all the galaxy clusters in the archive of the X-ray telescope ASCA. We determine the abundances of Fe, Si, S, and Ni as a function of cluster temperature (mass) from 1 – 10 keV, and place strong upper limits on the abundances of Ca and Ar. In general, Si and Ni are overabundant with respe...

Rapid neutron-capture (i.e., r-process) nucleosynthesis calculations, employing internally consistent and physically realistic nuclear physics input (QRPA β-decay properties and the recent ETFSI-Q nuclear mass model), have been performed. These theoretical computations assume the classical waiting-point approximation of (n,γ) ← (γ,n) equilibrium. The calculations reproduce the solar isotopic r-...