Testing the Disk-locking Paradigm: An Association between U - V Excess and Rotation in NGC 2264

We present some results from a UVI photometric study of a field in the youngopen cluster NGC 2264 aimed, in part, at testing whether accretion in pre-mainsequence stars is linked to rotation. We confirm that U-V excess is wellcorrelated with H-alpha equivalent width for the stars in our sample. We showthat for the more massive stars in the cluster sample (roughly 0.4-1.2 M_sun)there is also a significant association between U-V excess and rotation, in thesense that slow rotators are more likely to show excess U-band emission andvariability. This constitutes significant new evidence in support of thedisk-locking paradigm.Comment: Accepted by ApJ Letter