相关论文: Standard model atmospheres for A-type stars and no…
We present work on H alpha spectral line characteristics in PHOENIX stellar model atmospheres and their comparison to microlensing observations. We examine in detail the H alpha equivalent width (EW) and the line shape characteristics for…
We present a detailed study of the non-Local Thermodynamic Equilibrium (non-LTE) formation of the high-excitation neutral oxygen 777 nm triplet in MARCS model atmospheres representative of late-type stars with spectral types F to K. We…
Thermal surface radiation has been detected with X-ray instruments for several neutron stars with high spectral, spatial and timing resolution. These observations allow for direct study of fundamental properties of the source, but require…
The accuracy of measuring the basic parameters of neutron stars is limited in particular by uncertainties in chemical composition of their atmospheres. For example, atmospheres of thermally - emitting neutron stars in supernova remnants…
Convection is an important phenomenon in the atmospheres of A-type and cooler stars. A description of convection in ATLAS models is presented, together with details of how it is specified in model calculations. The effects of changing the…
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…
We discuss results of an exploratory non-LTE analysis of two metal-rich A-type supergiants in M31. Using comprehensive model atoms we derive accurate atmospheric parameters from multiple indicators and show that non-LTE effects on the…
Most of the physical information about astrophysical objects is obtained via the analysis of their electromagnetic spectra. Observed data coupled with radiation transfer models in physical conditions representative of stars, planets,…
Very massive stars (VMS) dominate the light of young stellar populations and are sources of intense stellar feedback. Their evolution is mainly driven by strong wind mass loss, yet current evolution models make simplistic assumptions on…
Spectral energy distributions for models of arbitrarily rotating stars are computed using two dimensional rotating stellar models, NLTE plane parallel model atmospheres, and a code to integrate the appropriately weighted intensities over…
NLTE effects - the errors caused by assuming local thermodynamic equilibrium (LTE) - on LiBeB abundance determinations for cool stars are discussed. These NLTE effects are significant in many cases for B I and Li I lines. The Be II 313 nm…
The effects of background line opacity (line-blocking) in statistical equilibrium calculations for Fe in late-type stellar atmospheres have been investigated using an extensive and up-to-date model atom with radiative data primarily from…
We investigate statistical equilibrium of neutral and singly-ionized strontium in late-type stellar atmospheres. Particular attention is given to the completeness of the model atom, which includes new energy levels, transition…
Non-LTE model atmospheres are in the forefront of quantitative spectral analyses of early type stars. Yet, such models are barely used in large surveys or even for individual systems. The major reason for this is likely the extreme…
We present Very Low Mass stellar models as computed including non-grey model atmospheres for selected assumptions about the star metallicities. The role of atmospheres is discussed and the models are compared with models based on the…
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…
We present a detailed investigation of atmospheres around accreting neutron stars with high magnetic field ($B\gtrsim 10^{12}$ G) and low luminosity ($L\lesssim 10^{33}$ erg/s). We compute the atmospheric structure, intensity and emergent…
Using a Hartree-Fock formalism, we estimate energy levels and photon cross sections for atomic iron in magnetic fields B ~ 10^13 G. Computing ionization equilibrium and normal mode opacities with these data, we construct LTE neutron star…
The intricate interplay of atmospheric shock waves and a complex, variable radiation field with non-equilibrium dust formation presents a considerable challenge to self-consistent modelling of atmospheres and winds of AGB stars.…
Here we present models of hot neutron star (NS) atmospheres consisting of thermonuclear ashes of various chemical compositions. These models are essential for studying thermonuclear flashes in X-ray bursting NSs in which nuclear-burning…