lithium burning

In astrophysics, the phrase lithium burning refers to any fusion reaction that begins with lithium (Li). Many stars carry it out near the beginning of their life because it naturally occurs during hydrogen burning. This depletes stars of lithium and they subsequently have less than the primordial abundance.

The reaction termed lithium burning occurs within one of the proton-proton chains: ⁷L is formed, the subsequent step combining ⁷L and hydrogen to produce two helium nuclei. Any stellar core hot enough to instigate this step is also hot enough to do the same to any preexisting lithium. The other stable lithium isotope, ⁶L, absorbs a proton and decays into ⁷L. Lithium can be evident in brown dwarfs because they undergo no such hydrogen burning.

Note that lithium is flammable, and outside astronomy, the phrase lithium burning generally refers to ordinary combustion (lithium's oxidation), something of general concern as lithium batteries grow more common.