The Li/Be Ratio in Main-Sequence Stars
Abstract
A spectroscopic study of the Li and Be content of some bright F and G main-sequence stars has been completed. The analysis was made with newly measured equivalent widths, a curve of growth, and line strengths predicted from a grid of model atmospheres. The data are combined with previously published results. Under the reasonable assumption that stars start with a common value for the ratio Li/Be, as evidenced by spallation experiments, it is possible to trace out the pattern of Li destruction. The change of Li/Be among main-sequence stars can be interpreted as an age effect. It is found that F stars deplete Li on a time scale longer than the age of the Hyades (tv> 5 X 108 years). Since G stars deplete Li on a time scale shorter than this (10~ < t~ < 10~ years) there must be an inverse relation between the Li destruction rate and spectral type. Since some very old G stars still have appreciable amounts of Li, either the depletion of Li ceases before these stars leave the main sequence or Li is formed anew in subgiants. The variation of Be abundance in main-sequence stars presumably represents differences in initial light-element content. There is evidence that this initial light-element content is generally smaller in the more massive stars. Several F stars contain no detectable Be (nor Li). Unless they have destroyed these elements after arrival on the main sequence, these stars must have had little or no initial light-element content I. INTRODUCTIO
Related Papers
- → Periodic light variations in four pre-main-sequence K stars(1983)70 cited
- → X-ray sources in regions of star formation. II - The pre-main-sequence G star HDE 283572(1987)33 cited
- → Automatic spectral classification of low-mass late-type stars(1999)1 cited
- → The Abundance of Gallium in B-Type Chemically Peculiar Stars(1986)
- → The number of Be stars compared with the number of B stars, taking into account the specific physical characteristics of Be stars(1994)