T-Tauri Stars
T-Tauri stars are young stars evolving onto the main sequence, frequently with large protoplanetary accretion disks. In fact, it is now recognized that there are two main types of T-Tauri stars, the classic (with strong Hydrogen-alpha absorption) and weak (weak Hydrogen-alpha absorbing). The weak T-Tauri's are now believed to be part of a binary star system, such that the protoplanetary disk is dispersed by tidal forces and is therefore short-lived.
Classic T-Tauri's have a narrow range of rotational periods centered on an 8-day period. Weak T-Tauri's have a broader range of rotational periods, thus it is concluded that disks have some sort of checking affect on the resulting rotational period. It is theorized that powerful stellar winds carry much of the inertia of the nascent star, and thus we end up systems like our own where almost all of the rotational inertia is in the planets and not the Sun.
Guy McArthur
