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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…
Active prominences exhibit plasma motions, resulting in difficulties with the interpretation of spectroscopic observations. These solar features being strongly influenced by the radiation coming from the solar disk, Doppler dimming or…
We estimate photospheric velocities of Type II-P supernovae using model spectra created with SYNOW, and compare the results with those obtained by more conventional techniques, such as cross-correlation, or measuring the absorption minimum…
Doppler radars are routinely used for the remote sensing of oceanic surface currents and atmospheric wind profiles. Even though they operate at different frequencies and address different media, they follow very similar processing for the…
Inspired by recent IRIS observations, we forward model the response of the Fe XXI 1354 \AA\ line to fundamental, standing, linear fast sausage modes (FSMs) in flare loops. Starting with the fluid parameters for an FSM in a straight tube…
The non-uniform surface temperature distribution of rotating active stars is routinely mapped with the Doppler Imaging technique. Inhomogeneities in the surface produce features in high-resolution spectroscopic observations that shift in…
This review paper outlines background information and covers recent advances made via the analysis of spectra and images of prominence plasma and the increased sophistication of non-LTE (ie when there is a departure from Local Thermodynamic…
Earlier studies have suggested that deviations from the local thermodynamic equilibrium (LTE) play a minor role in the formation of Be II 313 nm resonance lines in solar and stellar atmospheres. Recent improvements in the atomic data allow…
We describe a global parametric model for the observed power spectra of solar oscillations of intermediate and low degree. A physically motivated parameterization is used as a substitute for a direct description of mode excitation and…
We present the results of a statistical analysis of the Doppler shifts and the asymmetry parameters of V profiles of the Fe I 630.25 nm line produced by 2D MHD simulations of solar granulation. The realism of the simulations tested using…
An inversion technique has been developed to recover LTE one-dimensional model photospheres for late-type stars from very high-resolution high signal-to-noise stellar line profiles. It is successfully applied to the Sun using a set of…
We study the properties of line bisectors in the spectrum of the Sun-as-a-star, as observed using the Integrated Sunlight Spectrometer (ISS) of the SOLIS project. Our motivation is to determine whether changes in line shape, due to magnetic…
Observations of the Sun in the visible spectral range belong to standard measurements obtained by instruments both on the ground and in the space. Nowadays, both nearly continuous full-disc observations with medium resolution and dedicated…
We study all possible sources of inaccuracy in theoretical values of the photometric observables, i.e. amplitude ratios and phase differences, of early B-type main sequence pulsators. Here, we discuss effects of parameters coming from both…
The goal of this investigation is to study, in the line of previous works, the level of velocity fluctuations in different scenarios of the TJ-II stellarator. The method followed consists in measuring the apparent Doppler temperature of C4+…
We present a nonlinear Bayesian tomographic framework for Doppler spectral imaging that enables simultaneous reconstruction of emissivity, ion temperature, and flow velocity from line-integrated spectra. The method employs nonlinear…
Context. Departures from local thermodynamic equilibrium (LTE) distort the calcium abundance derived from stellar spectra in various ways, depending on the lines used and the stellar atmospheric parameters. The collection of atomic data…
The so-called full non-local thermodynamic equilibrium (FNLTE) radiative transfer problem allows us to take into account not only deviations of the radiation field from the Planckian but also deviations of the densities and velocity…
Motivated by both ground- and space-based detections of the sodium doublet in the transmission spectra of exoplanetary atmospheres, we revisit the theory and interpretation of sodium lines in non-local thermodynamic equilibrium (NLTE),…
Delta ($\delta$) sunspots sometimes host fast photospheric flows along the central magnetic polarity inversion line (PIL). Here we study the strong Doppler shift signature in the central penumbral light bridge of solar active region NOAA…