A cosmic abundance standard: chemical homogeneity of the solar neighbourhood and the ISM dust-phase composition
arXiv:0809.2403 · doi:10.1086/595618
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.
4 pages, 2 figures. Accepted for publication in ApJ Letters
References in corpus (4)
- Helioseismology and Solar Abundances
- The neon content of nearby B-type stars and its implications for the solar model problem
- Argon Abundances in the Solar Neighborhood: Non-LTE Analysis of Orion Association B-type Stars
- Is There Enhanced Depletion of Gas-Phase Nitrogen in Moderately Reddened Lines of Sight?