Table 1
Overview of the most important model parameter.
| Parameter | Value(s) | Comments | Reference |
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| Gridpoints | |||
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| {Mcl} | 10iM⊙ with i = −3,−2,...,3 | clump mass | |
| {ns} | 10i cm-3 with i = 3,4,...,7a | clump surface density | |
| {IUV} | 10iχ0 with i = −1,0,...,6 | FUV scaling factor | |
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| Abundances relative to the total hydrogen abundance | |||
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| He/H | 0.0851 | (1) | |
| O/H | 4.47(−4) | (2) | |
| C/H | 2.34(−4) | (2) | |
| 13C/H | 3.52(−6) | based on a 12C/13C ratio of about 67 in Orion | (3) |
| S/H | 7.41(−6) | (2) | |
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| Others | |||
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| α | 1.8 | clump-mass power law index | (4) |
| γ | 2.3 | mass-size power law index | (4) |
| Z | 1 | solar metallicity | |
| ζ CR | 2(−16) s-1 | cosmic ray primary ionisation rate per H2 | (5) |
| RV | 5.5b | ratio between visual extinction and “reddening” | (6) |
| for dense clouds | |||
| σg | 8.41(−22) cm2 | FUV dust cross section per H | (7) |
| b | 1 km s-1 | Doppler broadening parameterc | |
| AV/NH | 5.3(−22) cm2 | normalisation for extinction curve | (8) |
Notes. The numbers in parentheses indicate powers of ten.
For densities higher than 107 cm-3 the steep chemical gradient and short reaction time scales can cause numerical problems.
Correspondingly, we use an averaged, normalised extinction kFUV = ⟨ A(λ) /A(V) ⟩ λ = 1.722 with λ = 912...2066 Å (Röllig et al. 2013).
b = FWHM/ (4 ln 2)1/2, i.e. b = 1 km s-1 corresponds to FWHM = 1.67 km s-1 (Draine & Bertoldi 1996).
Reference. (1) Asplund et al. (2005); (2) Simón-Díaz & Stasińska (2011); (3) Langer & Penzias (1990); (4) Heithausen et al. (1998); (5) Hollenbach et al. (2012); (6) Draine & Bertoldi (1996); (7) Röllig et al. (2013); (8) Weingartner & Draine (2001a).
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