Astron. Astrophys. 347, 617-629 (1999)

Footnotes

1. Possibly due to the complexity of the atom in conjunction with the general difficulties encountered in non-LTE investigations concerning "ultra-cool stellar atmospheres" (see e. g. discussion in Luttermoser & Johnson 1992).

2. Shocks where the gas properties "jump" from their pre-shock to their post-shock values and where ambipolar diffusion is negligible.

3. http://aeldata.nist.gov/archive/holdp.html

4. http://cfa-www.harvard.edu/amp/data/kur23/sekur.html

5. http://vizier.u-strasbg.fr/OP.html

6. Most efficient in this case are the Fe I - forbidden transitions having Sobolev optical depths between at wavelengths 5060-5250 Å.

7. Most efficient in this case are the Fe II - fine-structure transitions at 26 µm and at 35.3 µm having Sobolev optical depths around .

8. Equivalent to the usage of Planck means in Eq. (24).

9. The terms "important" and "dominant" in this context concern the net local energy exchange between the gas and the radiation field, which is different from being important in radiative transfer or for the emergent spectrum.

10. This is the typical "nebular" case (e. g. Osterbrock 1974)

11. Supposed that some lines are present which are capable of driving the N-level system into the discussed case.

12. As long as the density of the carrier and the Einstein-coefficients of the lines assure optical thickness in the lines.

© European Southern Observatory (ESO) 1999

Online publication: June 30, 1999
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