Related papers: Clumping effects on non-thermal particle spectra i…

I develop a detailed empirical model for the chromosphere and wind of 31 Cyg based on a previously published analysis of IUE spectra from the 1993 eclipse and on the thermodynamics of how the wind must be driven. I then use this model to…

Massive, early-type stars deposit energy and momentum in the interstellar medium through dense, supersonic winds. These objects are one of the most important sources of ionising radiation and chemical enrichment in the Galaxy. The physical…

Context. The analysis of observations of circumstellar disks around young stellar objects is often based on models with a smooth and continuous density distribution. However, spatially resolved observations with increasing angular…

Recent observations of excess radiation at extreme ultraviolet and hard X-ray energies straddling the well known thermal soft X-ray emission have provided new tools and puzzles for investigation of the acceleration of nonthermal particles…

We have developed a numerical model for the temporal evolution of particle and photon spectra resulting from nonthermal processes at the shock fronts formed in merging clusters of galaxies. Fermi acceleration is approximated by injecting…

Synchrotron radiation of ultra-relativistic particles accelerated in a pulsar wind nebula may dominate its spectrum up to gamma-ray energies. Because of the short cooling time of the gamma-ray emitting electrons, the gamma-ray emission zone…

Evidence for nonthermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons, and new windows (in EUV and Hard X-ray ranges) have provided more powerful tools for its…

INTEGRAL tripled the number of super-giant high-mass X-ray binaries (sgHMXB) known in the Galaxy by revealing absorbed and fast transient (SFXT) systems. Quantitative constraints on the wind clumping of massive stars can be obtained from…

We examine whether nonthermal protons energized during a cluster merger are simultaneously responsible for the Coma cluster's diffuse radio flux (via secondary decay) and the departure of its intra-cluster medium (ICM) from a thermal…

Radio emission models of colliding wind binaries (CWBs) have been discussed by Dougherty et al. (2003). We extend these models by considering the temporal and spatial evolution of the energy distribution of relativistic electrons as they…

It was shown by dos Santos et al. the importance of Alfv\'en waves to explain the winds of Wolf-Rayet stars. We investigate here the possible importance of Alfv\'en waves in the creation of inhomogeneities in the winds of early-type stars.…

We present SPH simulations of protoclusters including the effects of winds from massive stars. Using a particle-injection method, we investigate the effect of structure close to the wind sources and the short-timescale influence of winds on…

In the subclass of high-mass X-ray binaries known as "microquasars", relativistic hadrons in the jets launched by the compact object can interact with cold protons from the star's radiatively driven wind, producing pions that then quickly…

We investigate the impact of optically thick clumping on stellar wind diagnostics in O supergiants and constrain wind parameters associated with porosity in velocity space. This is the first time the effects of optically thick clumping have…

Dense wind of a massive star can be partially captured by a neutron star (NS) inside a compact binary system. Depending on the parameters of NS and the wind, the matter can penetrate the inner NS magnetosphere. At some distance from the NS…

Magnetic fields on hot stars can produce a variety of interesting effects on the velocity, density, and temperature structure in the winds from the stars. The fields can produce a longitudinal dependence of the mass flux, which would lead…

Binary systems formed by early-type stars with strong winds are known to display variable non-thermal radio emission, thermal X-rays, and, at least in one case (Eta Carina), $\gamma$ rays. Some of these systems are quite eccentric and the…

Hot, massive (OB) stars experience strong line-driven stellar winds and mass loss. As the majority of efficient driving lines are metallic, the amount of wind driving and mass loss is dependent on the stellar metallicity Z. In addition,…

High-resolution X-ray spectra of O-type stars revealed less wind absorption than expected from smooth winds with conventional mass-loss rates. Various solutions have been proposed, including porous winds, optically thick clumps or an…

Analyzing the spectra from Wolf-Rayet stars requires adequate non-LTE modeling of their expanding atmosphere. The numerical schemes for solving the radiative transfer in the co-moving frame of reference have been developed by Mihalas and…