Non-LTE analysis of neutral copper in late-type metal-poor stars

Journal Article · Fri Mar 20 04:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/802/1/36· OSTI ID:22882619

Yan, H. L.; Shi, J. R.

We investigated the copper abundances of 64 late-type stars in the Galactic disk and halo with effective temperatures from 5400 to 6700 K and [Fe/H] from −1.88 to −0.17. For the first time, the copper abundances are derived using both local thermodynamic equilibrium (LTE) and non-local thermodynamic equilibrium (non-LTE) calculations. High-resolution (R>40,000), high signal-to-noise ratio (S/N>100) spectra from the FOCES spectrograph are used. The atmospheric models are calculated based on the MAFAGS opacity sampling code. All the abundances are derived using spectrum synthesis methods. Our results indicate that the non-LTE effects of copper are important for metal-poor stars, showing a departure of ∼0.17 dex at a metallicity of ∼−1.5. We also find that the copper abundances derived from non-LTE calculations are enhanced compared with those from LTE. The enhancements show clear dependence on the metallicity, which gradually increases with decreasing [Fe/H] for our program stars, leading to a flatter distribution of [Cu/Fe] with [Fe/H] than previous work. There is a hint that the thick- and thin-disk stars have different behaviors in [Cu/Fe], and bending of the disk stars may exist.

• OSTI ID: 22882619
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 802; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABUNDANCE
COMPARATIVE EVALUATIONS
COPPER
DISTRIBUTION
GALACTIC EVOLUTION
GALAXIES
LTE
METALLICITY
RESOLUTION
SIGNAL-TO-NOISE RATIO
SPECTRA
STARS
THERMODYNAMICS