Related papers: The solar oxygen crisis: Probably not the last wor…
The Mg/Ne abundance ratio in the quiet Sun is measured in both network and supergranule cell centre regions through EUV spectra from the Coronal Diagnostic Spectrometer on SOHO. Twenty four sets of data over the period 1996 March to 1998…
An analysis using modern atomic data of fluxes culled from the literature for O VIII and Ne IX lines observed in solar active regions by the P78 and Solar Maximum Mission satellites confirms that the coronal Ne/O abundance ratio varies by a…
Monte Carlo calculations of the Ne K$\alpha$ line fluoresced by coronal x-rays and emitted near the temperature minimum region of the solar atmosphere have been employed to investigate the use of this feature to measure directly the solar…
We investigate statistical equilibrium of Cr in the atmospheres of late-type stars. The main goal is to ascertain the reason for a systematic abundance discrepancy between Cr I and Cr II lines, which is often encountered in spectroscopic…
We present long-slit spectrophotometric observations in the red and near infrared of 12 HII galaxies. The spectral range includes the sulphur lines [SII] at wavelengths 6716, 6731 angstroms and [SIII] at 6312 angstroms and 9069, 9532…
Context: The scattering polarization of the infrared (IR) triplet of neutral oxygen (O\,\textsc{i}) near 777\,nm provides a powerful diagnostic of solar atmospheric conditions. However, interpreting such polarization requires a rigorous…
Element abundance ratios of magnesium to neon (Mg/Ne) and neon to oxygen (Ne/O) in the transition region of the quiet Sun have been derived by re-assessing previously published data from the Coronal Diagnostic Spectrometer on board the…
We present results of NTT spectroscopy of the one known planetary nebula (PN) in the dwarf spheroidal galaxy Fornax, a gas-deficient Local Group galaxy that stopped its star formation activity a few hundred million years ago. We detected…
The RESIK instrument on {\em CORONAS-F} spacecraft observed several sulphur X-ray lines in three of its four channels covering the wavelength range 3.8-6.1 \AA\ during solar flares. The fluxes are analyzed to give the sulphur abundance.…
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…
The magnetic field of the quiet-Sun chromosphere remains a mystery for solar physicists. The reduced number of chromospheric lines are intrinsically hard to model and only a few of them are magnetically sensitive. In this work, we use a 3D…
The solar chemical abundances studied in considerable detail because of discrepant values of solar metallicity inferred from different indicators, where in the present work we have used 28 suitable atomic spectral solar nitrogen lines,…
We present a dataset of high resolution spectra of the Sun and ten bright stars of the domains [6297-6303] and [6361-6367] Angtr{\"o}m. Solar spectra were obtained in the quiet Sun at various distances from disk centre with the ground based…
The compositions of stars are a critical diagnostic tool for many topics in astronomy such as the evolution of our Galaxy, the formation of planets, and the uniqueness of the Sun. Previous spectroscopic measurements indicate a large…
Neutral sodium is an important tracer of the Galactic chemical evolution, a powerful diagnostic of different stellar populations, and the subject of detailed studies of exoplanet atmospheres via transmission spectroscopy. This work aims to…
The low-luminosity dwarf irregular galaxies are considered. The oxygen abundances in HII regions of dwarf irregular galaxies were recalculated from published spectra through the recently suggested P - method. It has been found that the…
Aims. We investigate statistical equilibrium of Cr in the atmospheres of late-type stars to show whether the systematic abundance discrepancy between Cr I and Cr II lines, as often encountered in the literature, is due to deviations from…
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…
We present a new determination of the metallicity gradient in M33, based on Keck/LRIS measurements of oxygen abundances using the temperature-sensitive emission line [OIII] 4363 A in 61 HII regions. These data approximately triple the…
Observations of the QSO 0000-2620 with UVES spectrograph at the 8.2m ESO KUEYEN telescope are used for abundance analysis of the damped Ly-alpha system at z_{abs}=3.3901. Several Oxygen lines are identified in the Ly_alpha forest and a…