In this paper , we present a detailed high-resolution spectroscopic study of post main sequence stars in the Globular Cluster M68 .
Our sample , which covers a range of 4000 K in T _ { eff } , and 3.5 dex in log ( g ) , is comprised of members from the red giant , red horizontal , and blue horizontal branch , making this the first high-resolution globular cluster study covering such a large evolutionary and parameter space .
Initially , atmospheric parameters were determined using photometric as well as spectroscopic methods , both of which resulted in unphysical and unexpected T _ { eff } , log ( g ) , \xi _ { t } , and [ Fe/H ] combinations .
We therefore developed a hybrid approach that addresses most of these problems , and yields atmospheric parameters that agree well with other measurements in the literature .
Furthermore , our derived stellar metallicities are consistent across all evolutionary stages , with \langle [ Fe/H ] \rangle = - 2.42 ( \sigma = 0.14 ) from 25 stars .
Chemical abundances obtained using our methodology also agree with previous studies and bear all the hallmarks of globular clusters , such as a Na-O anti-correlation , constant Ca abundances , and mild r -process enrichment .