Related papers: Grains in Photo-Ionized Environments
Ever since the pioneering study of Spitzer, it has been widely recognized that grains play an important role in the heating and cooling of photo-ionized environments. A detailed code is necessary to model grains in a photo-ionized medium.…
In this paper we present results obtained with the new grain code in Cloudy which underline the strong effect of photo-electric heating by grains in photo-ionized regions. We study the effect that the distribution of grain sizes has on the…
The luminosity of the central source in ionizing radiation is an essential parameter in a photoionized environment, and one of the most fundamental physical quantities one can measure. We outline a method of determining luminosity for any…
The gas that is present in the interstellar medium is usually very far removed from (local) thermodynamic equilibrium, and in some cases may also not be in a steady-state equilibrium with its surroundings. The physics of this material is…
We have analyzed the effects of photoelectric heating by dust grains in photoionization models of planetary nebulae. We have shown that this process is particularly important if planetary nebulae contain a population of small grains. The…
We study the effects of using the optical properties of irregular hexahedral grains in photoionization models of circumstellar nebulae around evolved stars. Dust opacities for the irregular grains were obtained from the scattering…
A detailed study of interstellar polarization efficiency toward molecular clouds is used to attempt discrimination between grain alignment mechanisms in dense regions of the ISM. Background field stars are used to probe polarization…
The presence of charged dust grains is known to have a profound impact on the physical evolution of the multiphase interstellar medium (ISM). Despite its importance, this process is still poorly explored in numerical simulations due to its…
Dust grains play a major role in many astrophysical contexts. They affect the chemical, magnetic, dynamical, and optical properties of their environment, from galaxies down to the interstellar medium, star-forming regions, and…
With the high-resolution spectroscopy now available in the optical and satellite UV, it is possible to determine the neutral/ionized column density ratios for several different elements in a single cloud. Assuming ionization equilibrium for…
A model of spheroidal particles is used to calculate the steady-state temperature of dust grains immersed in the interstellar radiation field. It is found that the temperature of non-spherical grains with the aspect ratios a/b <= 2 deviates…
Icy grains in the interstellar medium and star-formation regions consist of a variety of materials. Such composite grains interact differently with cosmic-ray (CR) particles compared to simple single-material grains. We aim to calculate the…
This is a summary of the 2013 release of the plasma simulation code Cloudy. Cloudy models the ionization, chemical, and thermal state of material that may be exposed to an external radiation field or other source of heating, and predicts…
The temperatures of dust grains play important roles in the chemical evolution of molecular clouds. Unlike large grains, the temperature fluctuations of small grains induced by photons may be significant. Therefore, if the grain size…
Photoelectric emission from dust plays an important role in grain charging and gas heating. To date, detailed models of these processes have focused primarily on grains exposed to soft radiation fields. We provide new estimates of the…
As part of the Herschel Guaranteed Time Key Project MESS (Mass loss of Evolved StarS) we have imaged a sample of planetary nebulae. In this paper we present the PACS and SPIRE images of the classical bipolar planetary nebula NGC 650. We…
In this paper we study new infrared spectra of the evolved planetary nebula NGC 6445 obtained with ISO. These data show that the thermal emission from the grains is very cool and has a low flux compared to H beta. A model of the ionized…
Atomic species in the interstellar medium (ISM) transition out of their gas phase mainly by depletion onto dust. In this study, we examine if there is any change to the spectral line ratio predictions from a photoionization model of the…
Our understanding of physical processes in Photodissociation regions or Photon Dominated Regions (PDRs) largely depends on the ability of spectral synthesis codes to reproduce the observed infrared emission-line spectrum. In this paper, we…
We developed a new quick pseudo-3D photoionization code based on Cloudy (G. Ferland) and IDL (RSI) tools. The code is running the 1D photoionization code Cloudy various times, changing at each run the input parameters (e.g. inner radius,…