The Chemical Composition of the Small Magellanic Cloud H II Region NGC 346 and the Primordial Helium Abundance

By M. Peimbert, A. Peimbert, M. Ruiz. 2000

158 citations recorded by the source corpus.

Spectrophotometry in the λλ3400-7400 range is presented for 13 areas of the brightest H II region in the SMC: NGC 346. The observations were obtained at CTIO with the 4 m telescope. Based on these observations, its chemical composition is derived. The helium and oxygen abundances by mass are given by Y(SMC) = 0.2405 ± 0.0018 and O(SMC) = 0.00171 ± 0.00025. From models and observations of irregular and blue compact galaxies it is found that ΔY/ΔO = 3.5 ± 0.9 and, consequently, that the primordial helium abundance by mass is given by Yp = 0.2345 ± 0.0026 (1 σ). This result is compared with values derived from big bang nucleosynthesis and with other determinations of Yp.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/8cb705ede0711be2f0b78c82beb4314a06560aed

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Citations in the corpus

• Quantitative Spectroscopy of O Stars at Low Metallicity: O Dwarfs in NGC 346 (2003, unknown): “¼ 0:15–0.19 (Venn 1999; Peimbert et al. 2000).”
• Stellar evolution with rotation. VII. - Low metallicity models and the blue to red supergiant ratio in the SMC (2001, unknown): “Values of Yp between 0.23 and 0.24 are given in the literature (see e.g. Pagel et al. 1992; Izotov et al. 1997; Peimbert et al. 2000).”
• KECK HIRES SPECTROSCOPY OF EXTRAGALACTIC H ii REGIONS: C AND O ABUNDANCES FROM RECOMBINATION LINES (2009, methodology): “We have determined the He+/H+ ratio for t2 = 0 and t2 > 0 from a maximum likelihood method (Peimbert et al. 2000, 2002).”
• The VLT-FLAMES survey of massive stars: surface chemical compositions of B-type stars in the Magellanic Clouds (2006, background): “The interstellar material can be directly sampled via, for example, H ii regions (Dufour 1984; Russell & Dopita 1990; Peimbert et al. 2000; Kurt & Dufour 1998) but such studies may be complicated by depletion onto dust grains.”
• Escape of Ionizing Radiation from High-Redshift Galaxies (2007, background): “Note that emission line studies (Peimbert et al. 2000; Keller & Wood 2006) usually indicate somewhat larger values for both metallicities than the absorption line metallicities that we adopt.”
• The Primordial Abundance of 4He: A Self-consistent Empirical Analysis of Systematic Effects in a Large Sample of Low-Metallicity H II Regions (2007, methodology): “Second, the ratio of the number of dust particles to the number of hydrogen atoms in our objects is more than 1 order of magnitude lower than the ratio in the interstellar medium of the Galaxy, as shown by Izotov et al. (2006) in their study of SDSS extragalactic H ii regions.”
• Systematic Effects and a New Determination of the Primordial Abundance of 4He and dY/dZ from Observations of Blue Compact Galaxies (2003, methodology): “They use the expression from Peimbert et al. (2000) weighting by errors of line fluxes, while we use equation (1) weighting by errors of He abundances.”
• Revised Stellar Temperatures for Magellanic Cloud O Supergiants from Far Ultraviolet Spectroscopic Explorer and Very Large Telescope UV-Visual Echelle Spectrograph Spectroscopy (2002, background): “Besides, it suffers a similar depletion as carbon (Peimbert et al. 2000).”
• Revised Primordial Helium Abundance Based on New Atomic Data (2007, methodology): “The Y / O value derived by Peimbert et al. (2000) from observational results and models of chemical evolution of galaxies amounts to 3:5 0:9.”