T Tauri Stars
- Category of erratic variable stars which have yet to reach the main sequence of the Hertzsprung-Russell diagram. T Tauri itself is at the centre of a Herbig-Haro Object, which confirms its youth and the fact that Herbig-Haro Objects are associated with star formation. Their variability is probably linked to changes which occur before the star can become a stable, main-sequence star, and involves massive emissions of glowing gas into space It is possible that most or all main sequence stars have passed through a T Tauri stage. This possibility has been taken up in studies of the origin of the solar system, where the Sun’s T Tauri stage has been implicated in the distribution of angular momentum in the solar system.