Rotation in T Tauri stars. II - Clues for magnetic activity

The rotation rates of Bouvier et al. (1986) are used to study correlations between the rotation of T Tauri stars and their radiative energy losses in the X-ray range and in the H-alpha Ca II - K and Mg II - k lines. It is found that T Tauri star X-ray flux primarily depends on rotation, with a correlation between X-ray fluxes and rotation similar to that found for cool dwarfs and active binaries. It is suggested that this X-ray/rotation correlations is due to a solar-type magnetic dynamo. Also, it is shown that Ca II - K and Mg II - k losses scale with H-alpha line strength over three decades of flux from weak-line to classical and extreme T Tauri stars. Evidence for the existence of a solar-type magnetic dynamo in T Tauri stars and limits to the contribution of a magnetic dynamo to the atmospheric heating are examined.