This work presents a modified approach for calculating the electron collision operator in dense plasmas, focusing on singly ionized magnesium Mg II. We replace the standard Coulomb interaction energy with the Kelbg interaction energy to account for plasma screening and quantum diffraction effects. The collision operator is derived within the semi-classical impact approximation, where the total line width is expressed as the sum of weak and strong collisions. We systematically implement the Kelbg interaction energy across both contributions to account for modified electric fields and perturbed electron trajectories. Interference terms are neglected in the present work, consistent with Baranger’s criterion for isolated lines. Our results demonstrate significant deviations from pure Coulomb predictions, particularly at high densities and low temperatures, highlighting the importance of screened energies for accurate line-width calculations in plasma diagnostics.
We present new astrophysical parameters for the open cluster NGC 6793 based on new CCD UBV(RI)(KC) photometry. We derived a reddening of E(B-V)=0.24 +/- 0.02 mag and a heavy element abundance of Z=0.024 ( [Fe/H]=+0.20 dex). Padova isochrone fitting to the V & times;(B-V) colour-magnitude diagram yields an intermediate age of 525 +/- 51 Myr and a distance modulus of mu=8.80 +/- 0.05 mag, corresponding to a distance of d=575 +/- 58 pc from the Sun. The core radius of NGC 6793 appears to be shrinking due to advanced dynamical evolution ( log tau(2)=1.13 ), driven by mass segregation and the evaporation of low-mass stars from the central region. The ratios of core to half-mass radius ( Rc/Rh ) and half-mass to Jacobi radius ( R-h/R-J ) indicate that the cluster's evolution is governed by the combined effects of internal two-body relaxation, mass segregation, and external tidal perturbations. The ratio R-t/R-J=0.99 suggests that the cluster is currently in a tidally filling state. The parameter pairs ( t(diss)/t(rlx1)=40 , logR(J)/Rc=0.72 ) and ( R-h/R-J=0.38 , log rho(amb)=-0.88 ) place NGC 6793 among the relatively compact clusters within R-GC<7.9 kpc. This implies a compact internal structure that is stable against the combined effects of two-body encounters and tidal heating. Given its current state, NGC 6793 will likely dissolve and disperse before entering the final contraction phase ( R-4 regime).
We present , an efficient, open-source, general-purpose strong lens modeling package written in Julia. It supports single- and multi-plane lensing with a wide range of analytic lens profiles, and its modular design, built on Julia’s multiple dispatch, makes it straightforward to add new profiles or inference methods, while native multi-threading parallelizes the computationally expensive steps, enabling full cluster-scale lens reconstructions within hours on a desktop-class machine. We validate the mass-reconstruction pipeline of on two simulated galaxy clusters (Ares and Hera), recovering the convergence and magnification maps well where the lensing constraints lie, and on the JWST-observed cluster SMACS J0723.3–7327, obtaining a strong lens model (image-plane RMS of 0.46” ) consistent with previously published results. In addition, we introduce singularity maps as a complementary diagnostic for comparing lens models, probing differences in the higher-order derivatives of the lensing potential, which remain largely unconstrained by standard observables such as image positions, time delays, and flux ratios. is accompanied by a set of worked examples covering all core functionality.
NWA 5508 was characterized by SEM-EDS, micro-Raman, and infrared (IR) reflectance spectroscopy. SEM-EDS analysis identified Mg, Si, and Fe as the predominant elements, with Ca, Al, and S occurring as secondary constituents, indicative of heterogeneous Ca–Al-rich inclusions (CAIs) embedded within the matrix. Raman analyses identified olivine (Fo10-Fo100), kirschsteinite, enstatite (En90-En98), and hedenbergite, indicating both high-temperature nebular condensates and Fe-Ca-rich phases from oxidizing parent body processes. Magnetite is likely indigenous, while hematite, goethite, and Ca-sulfates are attributed to terrestrial alteration. IR spectroscopy confirmed primary silicates (olivine, pyroxene, and anorthite), refractory phases (diopside, melilite, spinel, and nepheline), carbonates, phyllosilicates, and organics. The combined data provides evidence for a complex geochemical history involving high-temperature nebular condensation, parent body metamorphism, aqueous alteration, and post-fall terrestrial processes. These results would contribute to the broader understanding of mineralogical diversity, alteration history, and formation conditions of CV3 chondrites, offering insights into the early solar system and parent body evolution.
We analyzed Total Electron Content (TEC) data from 22 GNSS (Global Navigation Satellite System) stations across Africa, Europe, and Asia, spanning equatorial, low, and mid-latitudes, to characterize daytime and nighttime ionospheric storm responses during the geomagnetic events of February 2014 and March 2015. Using a 5-min interval TEC dataset, we employed the threshold |rTEC ≤−30| or |rTEC ≥ 30| to identify positive and negative storm phases relative to a quiet-time defined by the median of the 10 quietest days. To investigate the underlying drivers of these phases, we examined variations in the ΔH-component from collocated magnetometers and evaluated spatial gradients to assess local time evolution and longitudinal variability. Our results show that ionospheric electrodynamics during storms are more strongly controlled by local time and geomagnetic longitude than by storm intensity, although storm strength still modulates the magnitude and spatial extent of the response. Notably, 18.97
