Abstract
view Abstract Citations (100) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Abundances in 10 H II regions in the Small Magellanic Cloud. Dufour, R. J. ; Harlow, W. V. Abstract A photoelectric study of selected emission lines in the spectral region from 3700 to 6800 A is reported for 12 positions in 10 of the most prominent H II regions in the Small Magellanic Cloud (SMC). Electron temperatures ranging from about 11,500 to 14,000 K are derived from the observed forbidden O III line intensities, and concentrations relative to H II are calculated for He II, N II, O II, O III, Ne III, and S II. An N(He)/N(H) ratio of approximately 0.081 is determined for the interstellar gas in the SMC; this is in reasonable agreement with previous results and rather similar to the value of approximately 0.084 for the Large Magellanic Cloud (LMC). Comparison of the He II/H II ratios in the SMC and LMC suggests that the observed abundance in the two clouds may be identical if corrections for He I are similar for the nebulae in both. The composition of the interstellar medium in the SMC is shown to be extremely homogeneous, and a metal deficiency of the interstellar gas is established which indicates that the LMC and SMC are representative of an earlier epoch in chemical evolution as compared with the Galaxy. It is concluded that the N enrichment in the two clouds has resulted mainly from primary nucleosynthesis processes. Publication: The Astrophysical Journal Pub Date: September 1977 DOI: 10.1086/155513 Bibcode: 1977ApJ...216..706D Keywords: Abundance; H Ii Regions; Interstellar Gas; Magellanic Clouds; Astronomical Spectroscopy; Cepheid Variables; Helium; Hydrogen Ions; Interstellar Extinction; Line Spectra; Metallic Stars; Nebulae; Radiant Flux Density; Thermal Emission; Astrophysics full text sources ADS | data products SIMBAD (13)
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