Temperature variations and N⁺/O⁺ in the Orion Nebula II. The collision strengths

We continue an investigation of electron temperature (T_e), mean-square T_e variation (t²), and the N ⁺/O⁺ abundance ratio. Our previous analysis of HST spectra of the Orion Nebula used collision strengths for N⁺ by Stafford et al. (1994). Here we examine the consequences of changing just these collision strengths by using those of Lennon & Burke (1994). Rather than utilize the standard analytical, low electron density (N_e) regime treatment for the analysis, we develop a numerical technique that is valid at any density. With Stafford et al. collision strengths, we find the average N_e for the (N⁺, O⁺)-zone is 7500 cm^-3, the average T_e is 9160 K, t² is 0.045, and N⁺/O⁺ is 0.14. Using Lennon & Burke values, the "best" solution is found when these respective quantities are: 9000 cm^-3, 9920 K, 0.00073, and 0.15. The value for t² is dramatically lower than that found using Stafford et al. data.