  We present a rotational study of Post-T Tauri stars (PTTSs) in Lindroos
systems, defined as binaries with early type primaries on the main-sequence
(MS) and late-type secondaries on the pre-main-sequence (PMS) phase. The
importance of this study in comparison with previous ones is that the Lindroos
sample is not X-ray selected so we avoid a possible bias towards fast rotators.
In this preliminary study we have monitored eleven stars in the UBVRI bands
during two campaigns of ten consecutive nights each. Eight of the observed
PTTSs show periodic modulations in their lightcurves and the derived periods
range from 1.9d to 8.0d. The comparison of these results with theoretical
rotational tracks based on disk-star locking theory shows that star-disk
decoupling times of 1-20 Myr could reproduce the rotational properties of the
targets, assuming an initial rotation period of ~8d and a mass of 1 Mo. We have
studied the rotation-activity relations of Lindroos PTTSs and compared them
with those found in other groups of PMS and zero-age main-sequence (ZAMS) ~1 Mo
stars. The Lindroos sample displays activity-rotation relations very similar to
those found in TTSs. It contains a mixture of very active stars, with Lx/Lbol
ratios close to the saturation level of -3, and less active (unsaturated)
stars. This could be the result of different star-disk decoupling times. Future
monitoring of a larger and unbiased sample of PTTS will be important to confirm
the significance of these results.
