MOCASSIN 2.02 manual

Running models that include dust and gas.

The gas and dust radiative transfer routines in MOCASSIN are now fully integrated. It is therefore now possible to run MOCASSIN in its original gas-only mode, as well as dust-only and of course dust+gas. The basics on how to run the code for dust-only or gas-only cases have already been given in pure photoionisation benchmarks and pure dust benchmarks; here we will concentrate on an example where both dust and gas are present.

Below is the file used for the dust and gas model of NGC 3918 as described by Ercolano, Barlow and Storey (2005, MNRAS, 362, 1038).

autoPackets 20. 2. 500000000
densityFile 'ngc3918/ngc3918den.dat'
multiChemistry 2 'ngc3918/ngc3918.dat' 'ngc3918/ngc3918.dat
contShape 'ngc3918/nLTe140lg65'
maxIterateMC  30 95.
nPhotons 1000000
nx 23
ny 23
nz 23
nbins 700
LStar 27.64
nuMax 23.7
nuMin 3.1e-4
Rin 0.
Rout 3.27142e17
TStellar 140000.
MdMh constant 0.0011
dustFile 'ngc3918/primary_grainspecies.dat' 'ngc3918/primary_grainsizes.dat'
writeGrid 50.
convLimit 0.03
resLinesTransfer 90.

In summary, it should be clear from the example above that the only keywords that differentiate the file above from the input of a gas-only model are:

Note that the first two keywords that define how much, what type and what size grains are to be used is also needed to run dust-only models (although MdMh could be substituted by Ndust or by MdMg). resLinesTransfer is only needed if there is gas also in the simulation (which would then be emitting resonance lines capable of heating the grains).

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