High-resolution, high signal-to-noise ratio spectra have been taken of seven K dwarf stars from the Pleiades cluster, in a very narrow range of colors. The aim of the experiment was to determine whether the large scatter in lithium abundances observed at any given color redder than (B — V)_0 = 0.8 (Soderblom et al. 1993a) is due to errors in the abundances derived from the resonance line of lithium at 6708 A. Since the resonance line is formed high in the atmosphere of the stars, it is questionable whether the equivalent width tells us useful information about the chemical abundance of lithium. Chromospheric emission (CE), for instance, could affect the measured equivalent width of the line. The subordinate line at 6104 A would not be so badly affected, since it is formed lower in a star's atmosphere. This report shows that there are, indeed, systematic differences in the lithium abundances derived from the two lines.
展开▼
