Te-fluctuations and N+/O+ in the Orion Nebula

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

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


Using the Faint Object Spectrograph (FOS) on the Hubble Space Telescope, we measured the flux of the N II] (2s2p3 5S2 → 2s22p2 3P2,1) lines at λvac = 2143.45, 2139.68 Å in the Orion Nebula. In order to assess the N+/O+ ratio, we also measured the flux of the [O II] (2p3 2P1/2,3/202P3 4S3/20) line at λvac = 2471.05, 2471.12 Å. In addition, with the FOS, other emission lines were measured in the same aperture in order to assess the average electron temperature and mean-square temperature variation (t 2) in the N+ region as well as the N+/O + ratio. When we require that the empirically-determined values be equal for (N+/O+)uv (obtained from the [O II] 2471 and N II] 2142 lines) and (N+/O+)opt (obtained from the [O II] 3728 and [N II] 6585 lines), we obtain the following. For the (N+, O+)-zone, the average electron density is ∼7000 cm-3, the average electron temperature is 9500 K, t 2 is 0.032, and N+/O+ is 0.14. In order to obtain N/O, the empirically-derived N+/O+ value requires a correction for the possibility that the N+ and O+ regions are not identical.

Original languageEnglish
Pages (from-to)34-41
Number of pages8
JournalRevista Mexicana de Astronomia y Astrofisica: Serie de Conferencias
StatePublished - 1998
Event6th Texas-Mexico Conference on Astrophysics: Astrophysical Plasmas - Near and Far - Houston, TX, United States
Duration: Mar 6 1997Mar 8 1997


  • H II regions
  • ISM: abundances
  • ISM: individual objects (Orion Nebula)

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics


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