The Abundance of Lithium in the Atmospberes of Cool Stars

Citation

Bonsack, Walter Karl (1959) The Abundance of Lithium in the Atmospberes of Cool Stars. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/HAVA-YH31. https://resolver.caltech.edu/CaltechETD:etd-01312006-133428

Abstract

The abundance of lithium relative to vanadium, or its upper limit, has been determined for forty-six normal stars of spectral types from G8 to MO, inclusive. These results are based upon high-dispersion spectrograms obtained with the coude spectrograph of the Hooker telescope. The abundance ratio for the sun has also been determined, using the equivalent width for lithium measured by Greenstein and Richardson and measurements of vanadiumm lines in the Utrecht Atlas. Values have also been obtained of quantities related to the physical conditions in the stellar atmoshperes. A range of up to a factor of one hundred in the abundance ratio is found among stars of similar surface characteristics. However, the maximum abundance ratio observed among similar stars declines with surface temperature. It is not likely that a significant part of the variation is due to vanadium abundance. Greenstein and Richardson have proposed that the lithuim in the solar surface has been depleted by convective mixing to hotter regions. It is suggested that this hypothesis may explain both the trend and the variations observed in the cooler stars.

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