**Table B.2:** Atomic data references for ORL analysis.
Ion	Effective recomb. coeffs.	Comment
H I	Storey & Hummer (1995)	Case B
He I	Benjamin et al. (1999)	Case B; singlets
	Brocklehurst (1972)	Case A; triplets
He II	Storey & Hummer (1995)	Case B
C II	Davey et al. (2000)	Case B
C III	Péquignot et al. (1991)	Case A
	Nussbaumer & Storey (1984)	Dielectronic recom.
C IV	Péquignot et al. (1991)	Case A
N II	Kisielius & Storey (2002)	Case B; triplets
	Escalante & Victor (1990)	Case A; singlets
N III	Péquignot et al. (1991)	Case A
	Nussbaumer & Storey (1984)	Dielectronic recom.
N IV	Péquignot et al. (1991)	Case A
	Nussbaumer & Storey (1984)	Dielectronic recom.
N V	Péquignot et al. (1991)	Case A
O II	Storey (1994)	Case B; quartets
	Liu et al. (1995)	Case A; doublets
O III	Péquignot et al. (1991)	Case A
O IV	Péquignot et al. (1991)	Case A
	Nussbaumer & Storey (1984)	Dielectronic recom.
O V	Péquignot et al. (1991)	Case A
Ne II	Kisielius et al. (1998)	Case B; doublets
	Storey (unpublished)	Case A; quartets
Mg II	Davey et al. (2000)^a	Case B

^a Given the similarity between the atomic structure of Mg II and C II, we have assumed that the Mg II 3d-4f $\lambda$ 4481 line has an effective recombination coefficient equal to that of the C II 3d-4f $\lambda$ 4267 line.

Source LaTeX | All tables | In the text

	1 Introduction
	2 Observations
	3 Raman scattering features
	4 Reddening summary
	5 Physical conditions
	6 Elemental abundances
	7 The central star
	8 Summary
	References
	Online Material
	Appendix A: Emission from heavy elements (Z>30)
	Appendix B: Atomic data references