Related papers: Variations on a theme - the evolution of hydrocarb…
Context. The properties of hydrogenated amorphous carbon (a-C:H) dust evolve in response to the local radiation field in the interstellar medium and the evolution of these properties is particularly dependent upon the particle size. Aims. A…
Context. The properties of hydrogenated amorphous carbon (a-C:H) dust are known to evolve in response to the local conditions. Aims. We present an adaptable model for the determination of the optical properties of low-temperature,…
Context. The evolution of amorphous hydrocarbon materials, a-C(:H), principally resulting from ultraviolet (UV) photon absorption- induced processing, are likely at the heart of the variations in the observed properties of dust in the…
Hydrogenated amorphous carbon (a-C:H) has been proposed as one of the carbonaceous solids detected in the interstellar medium. Energetic processing of the a-C:H particles leads to the dissociation of the C-H bonds and the formation of…
Hydrogenated amorphous carbon materials, a-C(:H), are heterogeneous structures consisting of carbon atoms in different hybridisation states and bonding configurations and are thought to constitute a significant and observationally important…
The nature and evolution of hydrocarbonaceous grains within interstellar and circumstellar media is still far from resolved, perhaps owing to the rather complex nature of their seemingly simple binary atomic compositions. This work explores…
A model of key processes influencing the evolution of a hydrocarbon grain of an arbitrary size under astrophysical conditions corresponding to ionized hydrogen regions (HII regions) and supernova remnants is presented. The considered…
We study evolution of hydrogenated amorphous carbon (HAC) grains under harsh UV radiation in photo-dissociation regions (PDRs) near young massive stars. Our aim is to evaluate the impact of the HAC grains on formation of observed small…
Observational evidence seems to indicate that the depletion of interstellar carbon into dust shows rather wide variations and that carbon undergoes rather rapid recycling in the interstellar medium (ISM). Small hydrocarbon grains are…
For amorphous carbon several laboratory extinction data are available, which show quite a wide range of differences due to the structural complexity of this material. We have calculated self-consistent dynamic models of circumstellar…
In order to deduce properties of dust in astrophysical environments where dust growth through aggregation is important, knowledge of the way aggregated particles interact with radiation, and what information is encoded in the thermal…
We present self-consistent dynamical models for dust-driven winds of carbon-rich AGB stars. The models are based on the coupled system of frequency-dependent radiation hydrodynamics and time-dependent dust formation. We investigate in…
Observations of diffuse clouds showed that they contain a number of simple hydrocarbons (e.g. CH, C$_2$H, (l- and c-)C$_3$H$_2$, and C$_4$H) in abundances that may be difficult to understand on the basis of conventional gas-phase chemical…
This work purports to help understand the InterStellar Extinction Curve in and near the visible range. In this range, crystalline materials are known to be transparent, so amorphous dust is needed. Molecular modeling experiments are used to…
Any distortion of a chemical structure causes new features to appear in the absorption spectrum of the structure, especially in the visible and near UV (see Paper I). Chemical modeling, using molecular orbital theory, showed that the…
Context. Hydrogenated amorphous carbons, a-C:H, can incorporate a variety of heteroatoms, which can lead to interesting effects. Aims. To investigate the doping of interstellar a-C:H grains with, principally, Si, O, N and S atoms within the…
Within the framework of The Heterogeneous dust Evolution Model at the IaS (THEMIS) this work investigates in detail the surface processes and chemistry relating to core/mantle interstellar and cometary grain structures and its influence on…
The interaction between hydrogen atoms and carbon nanoparticles is a fundamental process governing the properties of carbonaceous materials in environments ranging from combustion systems to the interstellar medium. This study investigates…
We propose a new description of astronomical dust emission in the spectral region from the Far-Infrared to millimeter wavelengths. Unlike previous classical models, this description explicitly incorporates the effect of the disordered…
With Planck and Herschel, we now have the spectral coverage and angular resolution required to observe dense and cold molecular clouds. As these clouds are optically thick at short wavelength but optically thin at long wavelength, it is…