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In the first three papers of this series, we investigated the formation of photospheric neutral iron lines in different atmospheres ranging from idealised flux tube models to complex three-dimensional magnetohydrodynamic (3D MHD)…

Solar and Stellar Astrophysics · Physics 2025-05-14 R. Holzreuter , H. N. Smitha , S. K. Solanki

Motivated by the controversy over the surface metallicity of the Sun, we present a re-analysis of the solar photospheric oxygen (O) abundance. New atomic models of O and Ni are used to perform Non-Local Thermodynamic Equilibrium (NLTE)…

The simple 3-D radiative transfer model in the atmosphere of the Earth is built for numerical comparison of direct solar radiation and limb scattering background at the definite layer during the deep twilight period at the middle and upper…

Atmospheric and Oceanic Physics · Physics 2025-09-05 Oleg S. Ugolnikov

We report an investigation of the suitability of quantum embedding for modeling the effects of the environment on the X-ray photoelectron spectra of hydrogen chloride and the chloride ions adsorbed on ice surfaces, as well as of chloride…

Chemical Physics · Physics 2023-05-10 Richard Asamoah Opoku , Céline Toubin , André Severo Pereira Gomes

The nanoflare paradigm of coronal heating has proven extremely promising for explaining the presence of hot, multi-million degree loops in the solar corona. In this paradigm, localized heating events supply enough energy to heat the solar…

Solar and Stellar Astrophysics · Physics 2020-09-02 Kalman J. Knizhnik , Will T. Barnes , Jeffrey W. Reep , Vadim M. Uritsky

Supernovae, with their diversity of compositions, velocities, envelope masses, and interactions are good testing grounds for probing the importance of NLTE in expanding atmospheres. In addition to treating H, He, Li I, O I, Ne I, Na I, and…

Astrophysics · Physics 2007-05-23 E. Baron , P. H. Hauschildt , P. Nugent , D. Branch

We investigate a non-equilibrium ionization state and an electron-ion two-temperature structure of the intracluster medium (ICM) in merging galaxy clusters using a series of N-body and hydrodynamic simulations. Mergers with various sets of…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Takuya Akahori , Kohji Yoshikawa

[Abridged] Clumping in the radiation-driven winds of hot, massive stars affects the derivation of synthetic observables across the electromagnetic spectrum. We implement a formalism for treating wind clumping - in particular the…

Solar and Stellar Astrophysics · Physics 2018-11-14 J. O. Sundqvist , J. Puls

Intermittent magnetohydrodynamical turbulence is most likely at work in the magnetized solar atmosphere. As a result, an array of scaling and multi-scaling image-processing techniques can be used to measure the expected self-organization of…

Astrophysics · Physics 2007-05-23 Manolis K. Georgoulis

Aims. We examined the capabilities of methods based on the weak-field approximation and line bisectors to extract fast and reliable information about the height stratification of the magnetic field and line-of-sight velocities,…

Solar and Stellar Astrophysics · Physics 2025-03-18 A. L. Siu-Tapia , L. R. Bellot Rubio , D. Orozco Suárez

The possibility of significant systematic errors due to the use of 1D homogeneous atmospheres in lithium-abundance determinations of cool stars motivates a study of non-local-thermodynamic-equilibrium (NLTE) effects on Li I line formation…

Astrophysics · Physics 2009-10-30 Dan Kiselman

Magnetic flux emergence has been shown to be a key mechanism for unleashing a wide variety of solar phenomena. However, there are still open questions concerning the rise of the magnetized plasma through the atmosphere, mainly in the…

Solar and Stellar Astrophysics · Physics 2020-01-15 D. Nóbrega-Siverio , F. Moreno-Insertis , J. Martínez-Sykora , M. Carlsson , M. Szydlarski

Large-scale stellar surveys, such as SDSS-V, 4MOST, WEAVE, and PLATO, require accurate atmospheric models and synthetic spectra of stars for accurate analyses of fundamental stellar parameters and chemical abundances. The primary goal of…

Solar and Stellar Astrophysics · Physics 2024-07-15 Philipp Eitner , Maria Bergemann , Richard Hoppe , Åke Nordlund , Bertrand Plez , Jonas Klevas

Recent HST observations suggest that the NLR in Seyfert Galaxies can be the result of interaction between jet and external inhomogeneous medium; following this suggestion we perform numerical simulations considering the impact of a…

Astrophysics · Physics 2007-05-23 P. Rossi , A. Capetti , G. Bodo , S. Massaglia , A. Ferrari

While solar flares are predominantly characterised by an intense broadband enhancement to the solar radiative output, certain spectral lines and continua will, in theory, exhibit flare-induced dimmings. Observations of transitions of…

Solar and Stellar Astrophysics · Physics 2021-05-26 Graham S. Kerr , Yan Xu , Joel C. Allred , Vanessa Polito , Viacheslav M. Sadykov , Nengyi Huang , Haimin Wang

Our knowledge of the heating mechanisms that are at work in the chromosphere of plage regions remains highly unconstrained from observational studies. The purpose of our study is to estimate the chromospheric heating terms from a plage…

Solar and Stellar Astrophysics · Physics 2022-08-10 R. Morosin , J. de la Cruz Rodríguez , C. J. Díaz Baso , J. Leenaarts

We use ground-based images of high spatial and temporal resolution to search for evidence of nanoflare activity in the solar chromosphere. Through close examination of more than 10^9 pixels in the immediate vicinity of an active region, we…

Solar and Stellar Astrophysics · Physics 2015-06-23 D. B. Jess , M. Mathioudakis , P. H. Keys

We present the non-local thermodynamic equilibrium (non-LTE) calculations for O I with the updated model atom that includes quantum-mechanical rate coefficients for O I + H I inelastic collisions from the recent study of Barklem (2018). The…

Solar and Stellar Astrophysics · Physics 2018-08-23 Tatyana Sitnova , Lyudmila Mashonkina

During solar flares a tremendous amount of magnetic energy is released and transported through the Sun's atmosphere and out into the heliosphere. Despite over a century of study, many unresolved questions surrounding solar flares are still…

Solar and Stellar Astrophysics · Physics 2022-12-14 Graham S. Kerr

We explore the response of the He II 304 {\AA} and He I 584 {\AA} line intensities to electron beam heating in solar flares using radiative hydrodynamic simulations. Comparing different electron beams parameters, we found that the…

Solar and Stellar Astrophysics · Physics 2015-12-14 Paulo J. A. Simões , Lyndsay Fletcher , Nicolas Labrosse , Graham S. Kerr
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