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

R. H. Rubin, R. J. Dufour, P. G. Martin, G. J. Ferland, J. A. Baldwin, C. O. Ortiz, D. K. Walter

Research output: Contribution to journalConference articlepeer-review


We continue an investigation of electron temperature (Te), mean-square Te 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 (Ne) 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 Ne for the (N+, O+)-zone is 7500 cm-3, the average Te 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.

Original languageEnglish
Pages (from-to)23-26
Number of pages4
JournalRevista Mexicana de Astronomia y Astrofisica: Serie de Conferencias
StatePublished - 2001
Event7th Texas-Mexico Conference on Astrophysics: Flows, Blows and Glows - Austin, TX, United States
Duration: Apr 6 2000Apr 8 2000


  • ISM: H II regions
  • ISM: abundances
  • ISM: individual: Orion Nebula

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics


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