Related papers: Continuum and Spectral Line Radiation from a Rando…
A variety of astronomical environments contain clouds irradiated by a combination of isotropic and beamed radiation fields. For example, molecular clouds may be irradiated by the isotropic cosmic microwave background (CMB), as well as by a…
We study the standard spectral line radiative transfer equation for media consisting of resonant atoms and non-resonant components (the dust grains and the atoms without considered spectral transition). Our goal is to study the intensity…
We present and discuss the results of new multiple-scattering radiative transfer calculations for three representative types of galactic environments, filled with either homogeneous or two-phase clumpy dust distributions. Extinction and…
We address light propagation properties in complex media consisting of random distributions of lenses that have specific focusing properties. We present both analytical and numerical techniques that can be used to study emergent properties…
Winds of massive stars are suspected to be inhomogeneous (or clumpy), which biases the measures of their mass loss rates. In High Mass X-ray Binaries (HMXBs), the compact object can be used as an orbiting X-ray point source to probe the…
We present analytical approximations for calculating the scattering, absorption and escape of nonionizing photons from a spherically symmetric two-phase clumpy medium, with either a central point source of isotropic radiation, a uniform…
We have investigated the effects of resonant scattering of emission lines on the image morphology and intensity from coronal loop structures. It has previously been shown that line of sight effects in optically thin line emission can yield…
In cold molecular clouds submillimetre emission lines are excited by the ambient radiation field. The pumping is dominated by the cosmic microwave background (CMB). It is usual in molecular line radiative transfer modelling to simply assume…
Mass-loss rates currently in use for hot, massive stars have recently been seriously questioned, mainly because of the effects of wind clumping. We investigate the impact of clumping on diagnostic ultraviolet resonance and optical…
Dust barriers effectively capture the photon momentum of a central light source, but low-density channels, along with re-emission at longer wavelengths, enhance its escape. We use Monte Carlo simulations to study the effects of…
In this paper we discuss the physical conditions of clumpy nature in the IC 348 molecular cloud. We combine new observations of fully sampled maps in [C I] at 492 GHz and 12CO 4--3, taken with the KOSMA 3 m telescope at about 1' resolution,…
In astrophysics, atomic transition line opacity is a primary source of uncertainty in theoretical calculations of radiative transfer. Much of this uncertainty is dominated by the inability to resolve the lines in frequency, leading to the…
Existing ubiquitously in the Universe with the highest luminosity, the Lyman-$\alpha$ emission line encodes abundant physical information about the gaseous medium it interacts with. Nevertheless, the resonant nature of Ly$\alpha$…
Sub-millimetre observations suggest that the filaments of interstellar clouds have rather uniform widths and can be described with the so-called Plummer profiles. The shapes of the filament profiles are linked to their physical state.…
We study the effects of optically thick clumps, non-void inter-clump medium, variation of the onset of clumping, and velocity dispersion inside clumps on the formation of resonance lines. For this purpose we developed a full 3-D Monte Carlo…
Context. Clumping is a common property of stellar winds and is being incorporated to a solution of the radiative transfer equation coupled with kinetic equilibrium equations. However, in static hot model atmospheres, clumping and its…
Broad emission lines are the most characteristic features in the spectra of active galaxies. They mostly show either a single-peaked or double-peaked profiles; and originate from a complex dynamics of the likely discrete clouds moving in a…
Several galaxies, such as dwarfs and Irregulars as well as outer galactic clouds have low metallicity. At low metallicities a reduction in the amount of dust and heavy elements plays a significant role on the chemistry as well as the…
The dense cloud associated with W40, one of the nearby H II regions, has been studied in millimeter-wave molecular lines and in 1.2 mm continuum. Besides, 1280 MHz and 610 MHz interferometric observations have been done. The cloud has…
This review describes the evidence for small-scale structure, `clumping', in the radiation line-driven winds of hot, massive stars. In particular, we focus on examining to what extent simulations of the strong instability inherent to…