This type of evolution is predicted by the disk-braking model. If all the stars in a given observation have lost their disks at a time in the sufficiently distant past, then all should be fast rotators. However, both here and in Edwards et al . Some stars may maintain their disks so long that by the time the braking mechanism has been removed the stellar core is close its final configurations. Similarities in the distribution of the slow rotators observed here and those observed in other star forming regions indicate that a similar mechanism controls the rotation of the slow rotators in all star forming regions.
Data suggest a link between existence of disks and the slow rotation.
While it is possible that stars in Orion OB1b have no internal braking, stars in Orion OB1a are almost certainly under the influence of such a mechanism. This new knowledge will allow future work to escape the selection effects which have hampered our understanding of how stars form. Many of these stars were subject to monitoring, but these data were excluded from the period searches since there was originally no reason to suspect any unusual behavior by these stars. Future planned observations also include deeper mapping of regions of star formation in V, R and I bands. Such data may allow us to search for the low end of the IMF and determine whether such an end exists.