We are familiar with the solar lithium problem. Lithium is of low abundance in the universe, and like the abundance of any element, this is a result of stellar nucleosynthesis. It is of even lower abundance in our sun, and this problem remains unsolved.  We are beginning to discover other places where anomalous concentrations of Lithium exist, and these stellar, interstellar, and exoplanetary lithium problems may fundamentally change the way we see star formation.

We know that Lithium ‘burns’ in the atmosphere of the sun at a certain depth, and it is thought that during different times in a star’s development, the convective cells extend to different depths.  The surface abundance of Li on the Sun is 140 times less than the protostellar concentrations would have been, and in general it is less than other stars that we have spectroscopically observed.  In some stars, this is complicated by rotation, which changes the hydrostatic equilibrium and pressure at different latitudes.  As it turns out, other stars with planets, like our own, are also lithium poor.  In metal-poor stars, such as generation II, the lithium abundance is above that predicted by the composition set by the big bang.

As we find out more about the lithium problem, our models for stellar physics will likely change.

The solar, exoplanet and cosmological lithium problems. J. Melendez, I. Ramirez, L. Casagrande, M. Asplund, B. Gustafsson, D. Yong, J. D. do Nascimento Jr., M. Castro, M. Bazot   http://arxiv.org/abs/0910.5845

Anders, E. and Grevesse, N. (January 1989). “Abundances of the elements – Meteoritic and solar”. Geochimica et Cosmochimica Acta 53 (1): 197–214. Bibcode:1989GeCoA..53..197A. doi:10.1016/0016-7037(89)90286-X