MOCASSIN 2.02 manual

Grain temperature spiking routines

The grain temperature spiking routines included in MOCASSIN are based on the Guhathakurta & Draine (1989 ApJ 345, 230) method. This is a very powerful method and allows the time-efficient computation of the time-dependent grain temperatures due to quantum heating. For the limitations of the method also see Siebenmorgen et al. (1992 A&A 266, 501). The temperature spikes only affect the output SED from dust grains, it is therefore advisable not to include these time consuming procedures until the model has almost converged in the case of gas+grain simulations (keep a high value of real2 - see quantumHeatGrain. In the gas of dust only models, it is worth to have the procedures working right from the start since the convergence criterion is then based on dust temperatures and therefore one must take this effect into account right from the start in order to avoid convergence fluctuations. It is in general not worth running the quantum heating routines on large grains that are unlikely to spike. For a discussion of the general cases when quantum heating routines must be considered please see Siebenmorgen et al. (1992 A&A 266, 501).

At present the grain temperature spiking routines are only implemented for carbonaceous or silicate grains. MOCASSIN will expect to be told what type of grain he is dealing with when calculating the spiking. This is done by adding a -capital- 'S' or 'C' at the beginnig of the species label in the optical constants file. e.g. for the Draine & Laor (1993) silicates data (dustData/sil-dlaor.nk):

Ssil_dl  1400. 3.3  0.588 20.077
0.10000E-02 0.99956E+00 0.97380E-04
0.10120E-02 0.99955E+00 0.10160E-03
0.10230E-02 0.99954E+00 0.10610E-03
0.10350E-02 0.99953E+00 0.11060E-03
0.10470E-02 0.99952E+00 0.11520E-03
0.10590E-02 0.99951E+00 0.12000E-03

Please email me if you would like to include T-spiking effects for other species.

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