NLTE Analysis of Copper Abundances in the Galactic Bulge Stars
  Based on the medium-high resolution (R~ 20,000), modest signal-to-noise ratio
(S/N > 70) FLAMES-GIRAFFE spectra, we investigated the copper abundances of 129
red giant branch stars in the Galactic bulge with [Fe/H] from -1.14 to 0.46
dex. The copper abundances are derived from both local thermodynamic
equilibrium (LTE) and nonlocal thermodynamic equilibrium (NLTE) with the
spectral synthesis method. We find that the NLTE effects for Cu I lines show a
clear dependence on metallicity, and they gradually increase with decreasing
[Fe/H] for our sample stars. Our results indicate that the NLTE effects of
copper are important not only for metal-poor stars but also for supersolar
metal-rich ones and the LTE results underestimate the Cu abundances. We note
that the [Cu/Fe] trend of the bulge stars is similar to that of the Galactic
disk stars spanning the metallicity range of -1.14 < [Fe/H] < 0.0 dex and the
[Cu/Fe] ratios increase with increasing metallicity when [Fe/H] is from~-1.2
to~-0.5 dex, favoring a secondary (metallicity-dependent) production of Cu.
