Aims. Lithium abundances for 19 metal-poor stars are determined using high-resolution spectroscopy. The abundances of stars on the lithium plateau are discussed. Methods. All abundance results are derived from NLTE statistical equilibrium calculations and spectrum synthesis methods.Results. In agreement with previous analyses it is found that excitation and de-excitation due to hydrogen collisions are negligible for the lithium line formation process, while charge transfer reactions are an important source of thermalization. However, the resulting NLTE effects on the determination of lithium abundances for metal-poor stars are negligible (<0.06 dex). Conclusions. The mean lithium abundance for stars on the lithium plateau determined from NLTE analyses is A(Li) ∼ 2.26, while it is 2.21 dex when charge transfer reactions are included. The latter result enhances the discrepancy between the observed lithium abundances and the primordial lithium abundance as inferred by the WMAP analysis of the cosmic microwave background. This discrepancy may be explained by metal diffusion.

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Inner-shell resonant absorption (IRA) effects were investigated on evolution dynamics of charge state distribution (CSD) in the interaction of ultraintense x-ray pulses with a neon atom. IRA is the physical origin of the large discrepancies found between theory and experiment at a photon energy of 1050 eV [L. Young et al., Nature (London) 466, 56 (2010)], where the rates of K-shell resonant absorption 1s → 4p of Ne 6+ and 1s → 3p of Ne 7+ are larger than the direct single-photon ionization rates by more than one order of magnitude, and hence IRA becomes the dominant absorption mechanism. Only when the IRA effects are properly taken into account can we correctly explain the observed CSD.

Nuclear dynamics in dense hydrogen, which is determined by the key physics of large-angle scattering or many-body collisions between particles, is crucial for the dynamics of planet's evolution and hydrodynamical processes in inertial confinement confusion. Here, using improved ab initio path-integral molecular dynamics simulations, we investigated the nuclear quantum dynamics regarding transport behaviors of dense hydrogen up to the temperatures of 1 eV. With the inclusion of nuclear quantum effects (NQEs), the ionic diffusions are largely higher than the classical treatment by the magnitude from 20% to 146% as the temperature is decreased from 1 eV to 0.3 eV at 10 g/cm3, meanwhile, electrical and thermal conductivities are significantly lowered. In particular, the ionic diffusion is found much larger than that without NQEs even when both the ionic distributions are the same at 1 eV. The significant quantum delocalization of ions introduces remarkably different scattering cross section between protons compared with classical particle treatments, which explains the large difference of transport properties induced by NQEs. The Stokes-Einstein relation, Wiedemann-Franz law, and isotope effects are re-examined, showing different behaviors in nuclear quantum dynamics.

There are systematic discrepancies unexplained so far between theory and experiment for opacities of mid- and high- Z plasmas. To address this issue, we investigated the radiative opacity of gold plasmas by using a detailed level-accounting (DLA) method, in which various physical effects can be taken into account. In this work, we studied in detail the effects of core-valence electron correlation and linewidth on the opacity of gold plasmas. Our DLA results correctly explain the relative intensity of the two strong absorption peaks located near the photon energies of 70 and 80eV , which was experimentally observed by Eidmann [Europhys. Lett. 44, 459 (1998)]. Meanwhile, the DLA results showed that effects of saturation for the strong individual lines are evident in the transmission spectrum.

We report calculations of energy levels and radiative rates for transitions among the lowest 116 fine-structure levels arising from the ⩽ n 5 configurations in Be-like ions with Z = 10-30. The wavelengths, oscillator strengths, line strengths, and radiative rates for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 116 levels have been calculated using the combined configuration interaction and many-body perturbation method. The accuracy of the results is determined through extensive comparisons with existing laboratory measurements and theoretical results. The present complete set of results should be of great help in line identification and the interpretation of spectra, as well as in the modeling and diagnostics of astrophysical and fusion plasmas.

The spectrally resolved radiative opacity and the Rosseland and Planck mean opacities are calculated by using the detailed-term-accounting approximation for aluminum plasmas with varieties of density and temperature. The results are presented along a 40 eV isothermal sequence, a 0.01 g/cm(3) isodense sequence, and a sequence with average ionization degree Z* approximately 7.13. Particular attention is given to the influence of the detailed treatment of spectral lines on the Rosseland mean opacity under different thermodynamic conditions. The results show that at densities of 0.004 g/cm(3) and higher, the opacities are not very sensitive to the spectral linewidth within a reasonable range. As examples, the Rosseland mean opacity, which is most sensitive to the detailed linewidth, at 40 eV and 0.004 g/cm(3) changes no more than 15%, when we change the electron impact spectral linewidth artificially by reducing it by 50% or increasing it twice, and at 40 eV and 0.1 g/cm(3) it changes less than 5%. For comparison, we also carried out calculations by using an average atom model. For the Rosseland mean opacities, the two models show quite large differences, in particular at low densities, while for the Planck mean opacities the results of the two models are much closer.