Context. We present the analysis of emission lines in high-resolution optical spectra of the planet-host star Proxima Centauri (Proxima) classified as a M5.5V. Aims: We carry out a detailed analysis of the observed spectra to get a better understanding of the physical conditions of the atmosphere of this star. Methods: We identify the emission

A new generation of solar instruments provides improved spectral, spatial, and temporal resolution, thus facilitating a better understanding of dynamic processes on the Sun. High-resolution observations often reveal multiple-component spectral line profiles, e.g., in the near-infrared He i 10830 Å triplet, which provides information about the

This article presents a statistical-mechanical treatment of a relationship (the force equation) between the gravitational potential for two particles and the correlation functions in a relaxed distribution of particles with different masses. This relationship is used in the case of galaxies interacting through a Newtonian potential in a Universe in

We show that kinematically peculiar cores may be generated in stellar spiral-spiral mergers. Kinematic segregation appears as the central bulges transport orbital angular momentum inward to the center of the remnant, while the outer parts keep the spin signature of the precursor disks. The peculiar core is composed mostly of bulge material, and its

We study the problem of the generation and transfer of spectral line intensity and polarization in models of stellar atmospheres with horizontal plasma inhomogeneities. We solve the non-LTE radiative transfer problem in full 3D geometry taking into account resonant scattering polarization and its modification by magnetic fields via the Hanle effect

Context. Lenticular galaxies (S0s) are more likely to host antitruncated (Type III) stellar discs than galaxies of later Hubble types. Major mergers are popularly considered too violent to make these breaks. Aims: We have investigated whether major mergers can result into S0-like remnants with realistic antitruncated stellar discs or not. Methods