Understanding the spin evolution of classical TTauri stars

The spin evolution of classical TTauri stars (CTTS) represents a puzzling problem. Since they are still contracting and accreting, these protostars would be expected to spin-up at breakup speed in a few million years. On the other hand, as soon as they emerge from the Class 0-I embedded phases, they are observed to rotate with periods between 1-10 days, well below their breakup limit. In addition, the evolution of the rotational distribution in open clusters of different ages suggests that TTauri stars do not dramatically spin up as long as they are surrounded by their accretion disks. An efficient spin-down mechanism is required to explain the spin evolution of CTTS. This poster presents a brief review of different mechanisms associated with the magnetic star-disk interaction that could determine the spin evolution of accreting pre-main-sequence stars. A suitable torque parametrization derived from numerical models can be used to compute the long-term evolution of stellar rotation. These results can provide different constraints to the models and shed light on our current understanding of the star-disk interaction process.