Related papers: Oxygen line formation in 3D hydrodynamical model a…

Context. Tighter constraints on metal-poor stars we observe are needed to better understand the chemical processes of the early Universe. Computing a stellar spectrum in 3D allows one to model complex stellar behaviours, which cannot be…

We investigate departures from LTE in the line formation of Fe for a number of well-studied late-type stars in different evolutionary stages. A new model of Fe atom was constructed from the most up-to-date theoretical and experimental…

We have performed a detailed oxygen abundance analysis of 23 metal-poor (-3.0<[Fe/H]<-0.3) unevolved halo stars and one giant through the OH bands in the near UV, using high-resolution echelle spectra. Oxygen is found to be overabundant…

This paper presents the results of a detailed theoretical investigation of the impact of non-LTE effects and of granulation inhomogeneities on the derived iron and oxygen abundances in the metal-poor halo subgiant HD140283. Our analysis is…

The Oxygen abundance in the solar photosphere, and consequently the solar metallicity itself, is still a controversial issue with far-reaching implications in many areas of Astrophysics. This paper presents a new determination obtained by…

We present the non-local thermodynamic equilibrium (non-LTE) calculations for O I with the updated model atom that includes quantum-mechanical rate coefficients for O I + H I inelastic collisions from the recent study of Barklem (2018). The…

Based on an exteded grid of NLTE, line blanketed model atmospheres with stellar winds as calculated by means of FASTWIND, we have investigated the change in the strengths of strategic Helium transitions in the optical as caused by a 0.3…

We study the evolution of gas in HII regions around the first stars after the death of the exciting stars. If the first star in a small halo dies without supernova (SN), subsequent star formation is possible in the same halo. We thus…

We extend our time-dependent hydrogen ionization simulations of diffuse ionized gas to include metals important for collisional cooling and diagnostic emission lines. The combination of heating from supernovae and time-dependent collisional…

As one of the most important elements in astronomy, iron abundance determinations need to be as accurate as possible. We investigate the accuracy of spectroscopic iron abundance analyses using archetypal metal-poor stars. We perform…

Context: Recent works with improved model atmospheres, line formation, atomic and molecular data, and detailed treatment of blends, have resulted in a significant downward revision of the solar oxygen abundance. Aims: Considering the…

We present results from a series of observational tests to 3D and 1D solar models. In particular, emphasis is given to the line formation of atomic oxygen lines, used to derive the much debated solar oxygen photospheric abundance. Using…

The atmospheres of massive O-type stars (O stars) are dynamic, turbulent environments resulting from radiatively driven instabilities over the iron bump, located slightly beneath the stellar surface. Here, complex radiation hydrodynamic…

An extremely high-resolution (> 10^5) high-S/N (> 10^3) solar spectrum has been used to measure 15 very weak first overtone (Delta v = 2) infrared OH lines, resulting in a low solar abundance of A(O) ~ 8.6 when MARCS, 3D, and spatially and…

The metal content of a galaxy is a key property for distinguishing between viable galaxy evolutionary scenarios, and it strongly influences many of the physical processes in the interstellar medium. An absolute and robust determination of…

We study the formation of B I lines in a grid of cool stellar model atmospheres without the assumption of local thermodynamic equilibrium (LTE). The non-LTE modelling includes the effect of other lines blending with the B I resonance lines.…

Due to their different nucleosynthetic origin, a stellar population produces oxygen (O) and iron (Fe) on different timescales and their relative abundance can deviate strongly from solar. Galaxy formation models should treat these elements…

In this review we discuss possible systematic errors inherent in classical 1D LTE abundance analyses of late-type stars for the light elements (here: H, He, Li, Be and B). The advent of realistic 3D hydrodynamical model atmospheres and the…

For the well studied halo star HD 122563 and the four stars in the globular cluster NGC 6397, we determine NLTE abundances of iron using classical plane-parallel model atmospheres. Each star reveals a discrepancy in abundances between the…

Recent studies of spectral lines of the CNO elements in the Sun and unevolved disk and halo stars show that most published abundance data may be affected by systematic errors due to inadequate 1D modelling of stellar atmospheres. This…