The lithium-rich giant stars puzzle

We suggest that the mass loss results from internal angular momentum transport. It is possible that a transitory instability, perhaps of magnetic origin, rapidly transports the nuclear material responsible for the lithium enrichment to the stellar surface and triggers shell ejections. Additionally, the strong mass loss in some lithium-rich stars during their evolution activates their chromospheres, as observed in ultraviolet spectra.

Furthermore, intense episodical mass losses in these stages lead to the observable formation of complex organic and inorganic particles, as detected in near-infrared spectra. In contrast to first-ascending giant stars, helium flashes during the clump can contribute to additional lithium enrichment alongside the aforementioned process. The combination of these two lithium sources may explain the much higher observed lithium abundances in clump stars as well as their observed infrared excesses.

If our scenario, based on a universal and rapid lithium enrichment episode process, is correct, it could explain the rarity of lithium-rich giant stars.