T Tauri phase

A phase through which low mass, pre-main sequence stars pass. The onset of nuclear fusion in the core of a young star brings about unstable pulsations and strong stellar winds. Unstable stars at this stage of their evolution are known as T Tauri stars. This phase is often associated with Herbig-Haro objects because the powerful outflows are colliding with the surrounding interstellar medium and causing shock emission. Collections of these stars are known as T Tauri associations.