The detection by IRAS of dust debris around Vega, Beta Pic
  and Fomalhaut provided the first evidence for solid material
  orbiting a main-sequence star other than the Sun.
  Vega is not precisely a young star (age 300 Myr), nor are
  some other similar objects.  The question then arises whether
  the debris is linked with still ongoing planet formation, or
  rather with the recent destruction of larger bodies.
  In order to answer this question we would like to compare the
  incidence of the Vega phenomenon in young and older stars.
  A mission scientist central proposal is dedicated to the study
  of the incidence of Vegatype stars in the solar vicinity, i.e.
  among a population of mostly older objects.
  We now propose to study the occurrence of the Vega phenomenon
  in A-type main sequence stars in nearby young clusters.  The
  best choice for such clusters appears to be IC2391 and IC2602.
  Both have turnoffs around spectral type B3, are not too crowded
  and nearby, and have a well populated A-star main sequence.
  ISO is needed for this project, because no excess is expected
  below 25 micron and because the fluxes are rather faint.
  If Vegatype disks occur in these clusters, however, they are
  within easy reach of PHOT.
  The proposal to observe two clusters, is linked with the fact
  that initial conditions may have an unknown effect on the
  phenomenon.  An important parameter may be stellar rotation.
  There are indications that stars in IC2602 rotate faster than
  stars in IC2391.