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We construct hydrogen atmosphere models for magnetized neutron stars in radiative equilibrium with surface fields B=10^12-5x10^14 G and effective temperatures T_eff a few x 10^5-10^6 K by solving the full radiative transfer equations for…
Nanometer- and micrometer-sized solid particles play an important role in the evolutionary cycle of stars and interstellar matter. The optical properties of cosmic grains determine the interaction of the radiation field with the solids,…
In a previous investigation, the orbital radii of regular satellites of Uranus, Jupiter, Neptune, and Saturn are shown to be directly related to photon energies in the spectra of atomic and molecular hydrogen. To explain these observations…
When stars form in small groups (N = 100 - 500 members), their circumstellar disks are exposed to little EUV radiation but a great deal of FUV radiation from massive stars in the group. This paper calculates mass loss rates for…
The effect of enhanced UV irradiation associated with stellar flares on the atmospheric composition and temperature of gas giant exoplanets was investigated. This was done using a 1D radiative-convective-chemical model with self-consistent…
The understanding of the evolution of early-type stars is tightly related to that of the effects of rapid rotation. For massive stars, rapid rotation combines with their strong radiation-driven wind. The aim of this paper is to investigate…
Observations indicate that outflows from massive young stars are more collimated during their early evolution compared to later stages. Our paper investigates various physical processes that impacts the outflow dynamics, i.e. its…
Transient spiral waves of moderate amplitude cause substantial changes to the angular momenta of many stars in a galaxy disk. Stars near to corotation are affected most strongly: for a wave of ~20% overdensity, the rms change for particles…
Radioactive decay of unstable atomic nuclei leads to liberation of nuclear binding energy in the forms of gamma-ray photons and secondary particles (electrons, positrons); their energy then energises surrounding matter. Unstable nuclei are…
Neutron stars are the densest, directly observable stellar objects in the universe and serve as unique astrophysical laboratories to study the behavior of matter under extreme physical conditions. This book chapter is devoted to describing…
The intensity and energy spectrum of energetic charged radiation in the heliosphere are significantly influenced by solar activity. This phenomenon is known as solar modulation of galactic cosmic rays. As interplanetary travel becomes a…
We examine various ways in which disk accretion can heat an accreting star. These include 1) radiation emitted from the disk surface which is intercepted by the stellar surface, 2) radiative flux directly across the disk-star interface, and…
Magnetic fields play such roles in star formation as the angular momentum transport in star-forming clouds, thereby controlling circumstellar disc formation and even binary star formation efficiency. The coupling between the magnetic field…
The atmospheres of highly irradiated exoplanets are observed to undergo hydrodynamic escape. However, due to strong pressures, stellar winds can confine planetary atmospheres, reducing their escape. Here, we investigate under which…
The aim of this research is to show that the processes of absorption charge-exchange and photo-association in $A+B^{+}$ collisions together with the processes of $AB^{+}$ photo-dissociation in the case of strongly non-symmetric ion-atom…
Stellar magnetic activity is a source of noise in the study of the transits of extrasolar planets. It induces flux variations which affect significantly the transit depth determination and the derivations of planetary and stellar…
Properties, structure, and thermal evolution of neutron stars are determined by the equation of state of stellar matter. Recent data on isospin-diffusion and isoscaling in heavy-ion collisions at intermediate energies as well as the size of…
2D axis-symmetric hydrodynamical simulations are presented which explore the interaction of stellar and disk winds with surrounding infalling cloud material. The star, and its accompanying disk, blow winds inside a cavity cleared out by an…
M-dwarf stars are generally considered favourable for rocky planet detection. However, such planets may be subject to extreme conditions due to possible high stellar activity. The goal of this work is to determine the potential effect of…
The importance of radiation pressure feedback in galaxy formation has been extensively debated over the last decade. The regime of greatest uncertainty is in the most actively star-forming galaxies, where large dust columns can potentially…