Burning of the most abundant isotope of lithium, lithium-7, occurs by a collision of lithium-7 and a proton producing beryllium-8, which promptly decays into two helium-4 nuclei.
T Tauri stars generally increase their rotation rates as they age, through contraction and spin-up, as they conserve angular momentum.
The P-P chain for lithium burning is as follows It will not occur in stars less than sixty times the mass of Jupiter.
Brown dwarfs at the high end of their mass range (60–75 MJ) can be hot enough to deplete their lithium when they are young.
Dwarfs of mass greater than 65 MJ can burn off their lithium by the time they are half a billion years old; thus, this test is not perfect.