The Lithium Plateau Enigma
نویسندگان
چکیده
Main-sequence Pop II stars stars with effective temperatures between 5500K and 6500K show a remarquably constant value for the lithium abundance (⇐⇒ the lithium plateau). Furthermore the dispersion around this value is very small (Bonifacio & Molaro 1997). However, from the observations of Pop I stars, there is strong evidence that the lithium abundance highly varies from star to star. The variation with Teff and age clearly appears in the galactic cluster data. From the theory and modelisation of stellar internal structure, lithium is expected to vary from star to star due to both nuclear destruction and/or element settling. These effects account well for the observations of Pop I stars, although more quantitative comparisons between observational and theoretical results are still needed. Helioseimology now provides a spectacular confirmation of the precision we have attained in the modelisation of the solar internal structure, including element settling (Richard et al. 1996). So why is the lithium abundance constant in the so-called lithium plateau while all predictions suggest that it should vary from star to star? Is there an “abundance attractor” which would work in Pop II stars but not in Pop I stars?
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تاریخ انتشار 1998