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arXiv · 0809.2403

A cosmic abundance standard: chemical homogeneity of the solar neighbourhood and the ISM dust-phase composition

Norbert Przybilla·Maria-Fernanda Nieva·Keith Butler
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Abstract

A representative sample of unevolved early B-type stars in nearby OB associations and the field is analysed to unprecedented precision using NLTE techniques. The resulting chemical composition is found to be more metal-rich and much more homogeneous than indicated by previous work. A rms scatter of ~10% in abundances is found for the six stars (and confirmed by six evolved stars), the same as reported for ISM gas-phase abundances. A cosmic abundance standard for the present-day solar neighbourhood is proposed, implying mass fractions for hydrogen, helium and metals of X=0.715, Y=0.271 and Z=0.014. Good agreement with solar photospheric abundances as reported from recent 3D radiative-hydrodynamical simulations of the solar atmosphere is obtained. As a first application we use the cosmic abundance standard as a proxy for the determination of the local ISM dust-phase composition, putting tight observational constraints on dust models.

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Norbert Przybilla, Maria-Fernanda Nieva, Keith Butler. 2008-10-24. A cosmic abundance standard: chemical homogeneity of the solar neighbourhood and the ISM dust-phase composition. https://doi.org/10.1086/595618

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