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2000ApJ...541..688P - Astrophys. J., 541, 688-700 (2000/October-1)

The chemical composition of the Small Magellanic Cloud H II region NGC 346 and the primordial helium abundance.


Abstract (from CDS):

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.

Abstract Copyright:

Journal keyword(s): Galaxies: Abundances - Galaxies: Individual: Name: Small Magellanic Cloud - Galaxies: ISM - ISM: H II Regions - ISM: Abundances - Galaxies: Magellanic Clouds

Simbad objects: 13

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