Pulsating variables in the Pleiades cluster

Thirty-one B and A stars in the Pleiades cluster were tested for short-period variability. Five a Scuti stars and one Be Shell variable were detected. The pulsation periods under 1 hour for the stars on the zero-age main sequence are predicted by the period-density relation. The period of 34 minutes for TR 31 is the shortest known so far for Cepheid4ike pulsation. The new variables extend the hot border of the instability strip to spectral type A2 on the zero-age main sequence.