Convective turnover times of disk-locking stars

We use the ATON stellar evolution code to calculate theoretical values of convective turnover times (tau_c_) and Rossby numbers (Ro, the ratio between rotation periods and tau_c_) for pre-main sequence (pre-MS) and main sequence (MS) stars. We investigate how tau_c_ varies with the initial rotation period and with the disk lifetime, using angular momentum conserving models and models simulating the disk-locking mechanism.

In the latter case, the angular velocity is kept constant during a given locking time to mimic the magnetic locking effects of a circumstellar disk. The local convective turnover times generated with disk-locking models are shorter than those obtained with angular momentum conserving models. The differences are smaller in the early pre-MS, increase with stellar age, and become more accentuated for stars with M>=1M_{sun} and ages greater than 100Myr.