  HD 34282 has been found to pulsate during a systematic search for short-term
photometric variability in Herbig Ae/Be stars with the goal of determining the
position and size of the pre-main sequence instability strip. Simultaneous
Stromgren photometry is used in the frequency analysis, yielding two
frequencies with values of nu1=79.5 and nu2=71.3 c/d. The light curve with the
largest amplitude is that of the u band. This behaviour, which is not common
for delta Scuti stars, is explained as pulsation in a high radial order in
stars near the blue edge of the instability strip. The main period, with a
value of 18.12 min, represents the shortest period observed so far for a delta
Scuti-type pulsator. A seismic modelling, including instability predictions and
rotation effects, has been attempted. It is found that both main sequence and
pre-main sequence models predict modes in the range of 56 to 82 c/d (between
648 and 949 microHz), corresponding to oscillations of radial order n from 6 to
8. The highest of the observed frequencies only becomes unstable for models of
low metallicity, in agreement with results from spectroscopic measurements.
