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The Abundance of Lithium and Convective Mixing in Stars of Type.
The abundance of lithium relative to vanadium, or its upper limit, hasbeen determined for forty-six normal stars of spectral types from G8 toMO, inclusive. These results are based upon high-dispersion spectrogramsobtained with the coude spectrograph of the 100-inch telescope. Theabundance ratio for the sun has also been determined, using anequivalent width for lithium measured by Greenstein and Richardson andmeasurements of vanadium lines in the Utrecht Atlas. In addition,temperatures, electron pressures, and turbulent velocities in thestellar atmospheres have been derived. A range of up to a factor of 100in the abundance ratio is found among stars of similar surfacecharacteristics. The maximum abundance ratio observed among similarstars declines with surface temperature. It is not likely that asignificant part of these variations is due to changes in the vanadiumabundance. Greenstein and Richardson have proposed that the lirnium inthe solar surface has been depleted by convective mixing to hotterregions. The possibility that this hypothesis may explain both the trendand the variations in the cooler stars is suggested and discussed.
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