Copper abundances are presented for 40 red-giant members of the massive Galactic globular cluster \omega Centauri , as well as 15 red-giant members of the globular clusters NGC288 , NGC362 , NGC3201 , NGC6752 , and M4 ( NGC6121 ) .
The spectra are of relatively high spectral-resolution and signal-to-noise .
Using these abundances , plus published literature values for field stars , the abundance trends of [ Cu/Fe ] are defined as a function of [ Fe/H ] .
The lowest metallicity stars in \omega Cen have [ Fe/H ] \sim -2.0 , with the stars in this sample spanning a range from [ Fe/H ] \sim -2.0 to -0.8 .
In the field star sample , [ Cu/Fe ] rises from about -0.8 , at [ Fe/H ] = -2.5 , to about -0.4 at [ Fe/H ] \sim -1.4 , and then rises rapidly to [ Cu/Fe ] \sim 0.0 at [ Fe/H ] =-1.1 .
The globular clusters ( other than \omega Cen ) tend to also follow the trend as displayed by the field stars .
Unlike the field stars , however , \omega Cen displays a constant ratio of [ Cu/Fe ] \sim -0.5 all the way to [ Fe/H ] =-0.8 .
At the metallicity of [ Fe/H ] = -0.8 , the values of [ Cu/Fe ] in \omega Cen fall below the corresponding mean ratio in the field stars by roughly 0.5 dex .
If copper is produced primarily in type Ia supernovae , as suggested in the literature , the lack of an increase in [ Cu/Fe ] in \omega Cen would suggest very little contribution from SN Ia to its chemical evolution within the metallicity range from [ Fe/H ] of -2.0 up to -0.8 .