On internal gravity waves in low-mass stars

The Sun's rotation profile and the lithium content of solar-type stars have long been challenging to stellar evolution. Classical hydrodynamical stellar models predict that the solar interior must rotate highly differentially, and produce over-destruction of lithium, in disagreement with asteroseismic and spectroscopic observations. The introduction of internal gravity waves (hereafter IGWs) in modem and sophisticated stellar models has recently solved these long-standing problems. Here we recall the main characteristics of these waves. We discuss the physics of wave generation and filtering as well as the existence of the so-called shear layer oscillation (SLO).