All Tables

Table 1: Spectral wavelength coverage and resolution of the spectra.
Table 2: Line ratios and electron densities derived using the default atomic parameters described in Table 3.
Table 3: References for default atomic parameters.
Table 4: References for O⁺ atomic data used to generate the loci plotted in Fig. 7.
Table 5: [O II] $\lambda 3729/\lambda 3726$ intensity ratios of low- $N_{\rm e}$ plasmas from literature.
Table 6: Extended diffuse emission regions around PNe that give a [S II] $\lambda 6716$ / $\lambda 6731$ ratio larger than 1.4 (from Kingsburgh & English 1992).
Table 7: Results of Kolmogorov-Smirnov Two-sample Test on densities deduced from the four optical $N_{\rm e}$ -diagnostic ratios. X and Y denote the two density samples for the test, D is the Kolmogorv-Smirnov D statistic of the samples, P₀(>|D|) gives the probability of exceeding |D| under the Null Hypothesis and is equal to 1 minus confidence factor, n is the size of the samples and $D(\alpha _{0.10})$ is the critical D value for a confidence factor of 0.10.