Related papers: Improved Stark Broadened Profiles for Neutral Heli…
We present a grid of spherically symmetric model atmospheres for young pre-MS stars. This grid spans the parameter range $2000\K \leq \Teff \leq 6800\K$ and $2.0 \leq \logg \leq 3.5$ for $M=0.1\Msun$, appropriate for low mass stars and…
Current stellar model predictions of adiabatic oscillation frequencies differ significantly from the corresponding observed frequencies due to the non-adiabatic and poorly understood near-surface layers of stars. However, certain…
This survey, once completed, will provide a 3D sample of 200 nearby spiral and irregular galaxies in the Halpha line, using a Fabry-Perot system. The data cubes obtained for each galaxy allow derivation of lines maps, velocity fields and…
We study chromospheric emission to understand the temperature stratification in the solar chromosphere. We observed the intensity profile of the CaIIH line in a quiet Sun region close to the disk center at the German Vacuum Tower Telescope.…
(Abridged) The color and luminosity distribution of horizontal branch (HB) stars in globular clusters are sensitive probes of their original helium abundances. However, recent analyses based on visual and near-ultraviolet (UV) CMDs have…
The purpose of this work is to explore the evolution of helium-core white dwarf stars in a self-consistent way with the predictions of detailed non-gray model atmospheres and element diffusion. To this end, we consider helium-core white…
Herschel has revolutionized our ability to measure column densities (N$_{\rm H}$) and temperatures (T) of molecular clouds thanks to its far infrared multiwavelength coverage. However, the lack of a well defined background intensity level…
Observations of deuterated species are useful in probing the temperature, ionization level, evolutionary stage, chemistry, and thermal history of astrophysical environments. The analysis of data from ALMA and other new telescopes requires…
Environments play an important role in galaxy formation and evolution, particularly in regulating the content of neutral gas. However, current HI surveys have limitations in their depth, which prevents them from adequately studying low HI…
This work presents a Bayesian algorithm to fit the recombination and collisionally excited line spectra of gas photoionized by clusters of young stars. The current model consists in fourteen dimensions: two electron temperatures, one…
We report measurements of the Stark shifts and Stark widths of sodium spectral lines corresponding to nS-3P and mD-3P transitions. Measurements have been made on AC driven high pressure NaHg and NaCd discharges. Electron density has been…
Gamma ray heating and neutrino cooling rates, due to weak interaction processes, on $sd$-shell nuclei in stellar core are calculated using the proton neutron quasiparticle random phase approximation theory. The recent extensive experimental…
Accurate spectroscopic lithium abundances are essential in addressing a variety of open questions, such as the origin of a uniform lithium content in the atmospheres of metal-poor stars (Spite plateau) or the existence of a correlation…
Stark broadening parameters for 36 multiplets of B IV have been calculated using the semi-classical perturbation formalism. Obtained results have been used to investigate the regularities within spectral series and temperature dependence.
We present the second part of our detailed analysis of the hot sdO and spectroscopic standard star BD+28 4211, in which we focus on the optical spectrum. In the first part of our study, we determined the abundances of some 11 metals…
The JWST and ALMA have detected emission lines from the ionized interstellar medium (ISM) in some of the first galaxies at $z \gtrsim 6$. These measurements present an opportunity to better understand galaxy assembly histories and may allow…
We utilize state-of-the-art 3D hydrodynamical and classical 1D stellar model atmospheres to study the influence of convection on the formation properties of various atomic and molecular spectral lines in the atmospheres of four red giant…
The 23 GHz emission lines from the NH3 rotation inversion transitions are widely used to investigate the kinematics and physical conditions in dense molecular clouds. The line profile is composed of hyperfine components which can be used to…
We present a modification of a model of solar cycle evolution of the solar Lyman-alpha line profile, along with a sensitivity study of interstellar neutral H hydrogen to uncertainties in radiation pressure level. The line profile model,…
High-resolution spectroscopic studies of solar-type stars have revealed higher iron abundances derived from singly ionized species compared to neutral, violating the ionization equilibrium under the assumption of local thermodynamic…