Related papers: Oxygen line formation in 3D hydrodynamical model a…
We compare current 1D and multi-dimensional atmosphere modelling approaches for massive stars to understand their strengths and shortcomings. We calculate averaged stratifications from selected 2D calculations for O stars -- corresponding…
Carbon monoxide (CO) is the primary tracer for interstellar clouds where stars form, yet CO has never been detected in galaxies with an Oxygen abundance relative to Hydrogen less than 20% of solar, even though such low metallicity galaxies…
In this contribution we present the first census of oxygen in star-forming galaxies in the local universe. We examine three samples of galaxies with metallicities and star formation rates at z = 0.07, 0.8 and 2.26, including the SDSS and…
We present non-Local Thermodynamic Equilibrium (non-LTE) calculations for neutral carbon spectral line formation, carried out for a grid of model atmospheres covering the range of late-type stars. The results of our detailed calculations…
Non-local thermodynamical equilibrium (NLTE) line formation for Mg I and Mg II lines is considered in classical 1D-LTE model atmospheres of the Sun and 17 stars with reliable atmospheric parameters and in a broad range of spectral types:…
Heavy-elements, i.e. those beyond the iron peak, mostly form via two neutron capture processes: the s- and r-process. Metal-poor stars should contain fewer isotopes that form via the s-process, according to currently accepted theory. It has…
The presence of 6Li in the atmospheres of metal-poor halo stars is usually inferred from the detection of a subtle extra depression in the red wing of the 7Li doublet line at 670.8 nm. However, the intrinsic line asymmetry caused by…
We present a model atom for C I - C II - C III - C IV using the most up-to-date atomic data and evaluated the non-local thermodynamic equilibrium (NLTE) line formation in classical 1D atmospheric models of O-B-type stars. Our models predict…
Un-evolved, very metal-poor stars are the most important tracers of the cosmic abundance of lithium in the early universe. Combining the standard Big Bang nucleosynthesis model with Galactic production through cosmic ray spallation, these…
Neutral Fe lines are the most abundant in the spectrum of late stars. They are used to obtain different basic stellar parameters such as relative abundances, surface gravity, and effective temperature. However, the centers of many of these…
Non-local thermodynamical equilibrium (non-LTE) line formation for neutral and singly-ionized iron is considered through a range of spectral types when the effective temperature varies from 6500 K up to 8500 K, the gravity from log g = 4…
The formation of stars and planetary systems is a complex phenomenon, which relies on the interplay of multiple physical processes. Nonetheless, it represents a crucial stage for our understanding of the Universe, and in particular of the…
Spatially resolved studies of star forming regions show that the assumption of spherical geometry is not realistic in most cases, with a major complication posed by the gas being ionised by multiple non-centrally located stars or star…
We compare the abundances of various chemical species as derived with 3D hydrodynamical and classical 1D stellar atmosphere codes in a late-type giant characterized by T_eff=3640K, log g = 1.0, [M/H] = 0.0. For this particular set of…
The non-local thermodynamic equilibrium (NLTE) line formation of neutral boron in the atmospheres of cool stars are investigated. Our results confirm that NLTE effects for the B I resonance lines, which are due to a combination of…
Among many physical processes involved in star formation, radiation transfer is one of the key processes since it dominantly controls the thermodynamics. Because metallicities control opacities, they are one of the important environmental…
We provide an extensive set of theoretical spectral energy distributions of massive stars derived from our "combined stellar structure and atmosphere models". The calculations covering the entire main sequence evolution for initial masses…
We have collected from different surveys some significant spectroscopic data observed from star-forming galaxies in the local Universe. The objects showing a relatively rich spectrum in number of lines from different elements were selected…
The study of carbon and oxygen abundances yields information on the time evolution and nucleosynthetic origins of these elements, yet remains relatively unexplored. At low metallicities (12+log(O/H) < 8.0), nebular carbon measurements are…
We present a detailed and uniform study of oxygen abundances in 155 solar type stars, 96 of which are planet hosts and 59 of which form part of a volume-limited comparison sample with no known planets. EW measurements were carried out for…