Astronomy and Astrophysics – Astrophysics
Scientific paper
2004-02-16
Mon.Not.Roy.Astron.Soc. 350 (2004) 1330
Astronomy and Astrophysics
Astrophysics
12 pages, 3 figures, 8 tables, minor typographical corrections wrt v1
Scientific paper
10.1111/j.1365-2966.2004.07734.x
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 will use the spectral synthesis code Cloudy for this purpose. The grain model of this code has recently undergone a comprehensive upgrade. Part of this is the newly developed hybrid grain charge model, which will be described in detail. This model allows discrete charge states of very small grains to be modelled accurately while simultaneously avoiding the overhead of fully resolving the charge distribution of large grains, thus making the model both accurate and computationally efficient. A comprehensive comparison with the fully resolved charge state models of Weingartner & Draine (2001) shows that the agreement is very satisfactory for realistic size distributions. The effect of the grain size distribution on the line emission from photo-ionized regions is studied by taking standard models for an H II region and a planetary nebula and adding a dust component to the models with varying grain size distributions. A comparison of the models shows that varying the size distribution has a dramatic effect on the emitted spectrum, and affects the ionization balance as well. These results clearly demonstrate that the grain size distribution is an important parameter in photo-ionization models.
Ferland Gary J.
Martin Peter G.
van Hoof Peter A. M.
Volk Kathryn
Weingartner Joseph C.
No associations
LandOfFree
Grain size distributions and photo-electric heating in ionized media does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Grain size distributions and photo-electric heating in ionized media, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Grain size distributions and photo-electric heating in ionized media will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-680228