Table 5:

Literature compilation of abundances estimates for PN G135.9+55.9.

Ref.	Spectral			He	C	N	O	Ne	C/O	N/O	Ne/O
	domain
T01	O	150	-				(0.5)
J02	O	100	17.6	10.82			6.93	7.47			3.47
R02	O	100	30	10.9			6.15 (0.35)	6.35			0.5 (0.3)
PT05	O	130	30	10.91			(0.3)	6.65			0.14 (0.14)
S05	O+U	-	-		7.51 (0.15)	6.87 (0.19)	6.85 (0.25)	6.6	4.7 (1.1)	1.05 (0.15)	0.65 (0.35)
J06	O+U	130	30a	10.87	7.58	6.94	7.18	6.66	2.5	0.58	0.30
this work	O+U	138	21.1	10.88	7.90	7.47:	6.74	6.96	14	5.4:	1.7
				11.04	8.89	8.39	8.65	8.01	1.74	0.55	0.23
BoBn-1				11.05	8.85	8.00	7.83	7.72	10.5	1.48	0.78

Notes. The table only includes estimates that are based on observed emission lines. Columns 1-4 specify the source reference, the wavelength range (O - optical, and U - UV), the stellar effective temperature ( ) and the mean electron temperature ( ) used in the study. Columns 5-9 give element abundances using the same units as in Table 2. In Cols. 10-12 we also give abundance ratios relative to oxygen. Uncertainties are, were provided, given in parentheses. A colon indicates an uncertain value of our best-match model. The abundances of our best-match model are given in the row marked this work. In the last two rows we, for comparison, give the mean abundance distribution of the Galactic disk ( ; Table 2) and the halo-PN BoBn-1 (the values of this object are taken from Howard et al. 1997). For further details see Sect. 5.
^(a) Jacoby (priv. comm.).