1998AJ....115..685L

We present spectroscopic evidence for small star-to-star variations in the abundance of the atoms from Ca to Ni (primarily Fe) among three bright giants in the metal-poor globular cluster M92: V-45, XI-19, and XII-8. Although all three have very similar B - V colors and visual magnitudes, weak ``iron peak'' absorption lines are typically about 15%-30% stronger in the spectrum of star XI-19. A line-by-line analysis shows that the abundances of the ``iron peak'' elements are very similar in stars V-45 and XII-8; the (logarithmic) mean difference is only 0.01 ± 0.01 dex for 106 lines. The average abundance of the ``iron peak'' elements is 0.18 ± 0.01 dex larger in XI-19 (121 lines). The very small ``internal'' error in the mean difference can be traced to (1) comparing the abundances one line at a time in order to avoid errors introduced by uncertain gf-values, (2) averaging equivalent widths for two spectra for both XI-19 and the comparison stars to reduce random errors in the equivalent widths, and (3) using a large number of lines to drive down the error in the mean. The ``external'' errors must also be small: the very small differences in the positions of the stars in the (V, B - V) color-magnitude diagram imply such similar values of T<sub>eff</sub> and log g that the line-strength differences must be due to real abundance differences. Comparison of small ``iron peak'' abundance variations with the larger variations that have been observed in the abundances of the light elements C, N, O, Na, Mg, and Al or the n-capture elements Ba and Eu in metal-poor Galactic globular clusters appears to be possible and may shed some light on the origins of both in the future.