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We utilize high-resolution (R~60,000), high S/N (~100) spectroscopy of 17cool Pleiades dwarfs to examine the confounding star-to-star scatter in the6707 Li I line strengths in this young cluster. Our Pleiads, selected for theirsmall projected rotational velocity and modest chromospheric emission, evincesubstantial scatter in the linestrengths of 6707 Li I feature that is absent inthe 7699 K I resonance line. The Li I scatter is not correlated with that inthe high-excitation 7774 O I feature, and the magnitude of the former isgreater than the latter despite the larger temperature sensitivity of the O Ifeature. These results suggest that systematic errors in linestrengthmeasurements due to blending, color (or color-based T_eff) errors, or lineformation effects related to an overlying chromosphere are not the principalsource of Li I scatter in our stars. There do exist analytic spot models thatcan produce the observed Li scatter without introducing scatter in the K I linestrengths or the color-magnitude diagram. However, these models predict factorof >3 differences in abundances derived from the subordinate 6104 and resonance6707 Li I features; we find no difference in the abundances determined fromthese two features. These analytic spot models also predict CN line strengthssignificantly larger than we observe in our spectra. The simplest explanationof the Li, K, CN, and photometric data is that there must be a real abundancecomponent to the Pleiades Li dispersion. We suggest that this real abundancecomponent is the manifestation of relic differences in erstwhilepre-main-sequence Li burning caused by effects of surface activity on stellarstructure. We discuss observational predictions of these effects.

Li I and K I Scatter in Cool Pleiades Dwarfs