The Time Spread of Star Formation in the Pleiades

Abstract

It is at least reasonable to believe that the time spread of star formation in a cluster could influence the resultant (averaged) IMF. If so, then we would expect a "universal" IMF within clusters only if the time spread of star formation was sensibly the same for all clusters. Alternatively, if the time spread of star forma- tion is highly variable in clusters, it would seem likely that their IMF’s should also be fairly variable. In fact, there have been a number of claims for large time spreads of star formation in open clusters, most notably the Pleiades. I will re- view the various claims of an age spread in the Pleiades and attempt to reconcile them.