NONRADIAL PULSATION OF THE UNEVOLVED HOT DELTA-SCUTI STAR CD-24-DEGREES-7599 DISCOVERED WITH THE WHOLE-EARTH-TELESCOPE

We report a frequency analysis of the delta Scuti star CD-24 degrees 7 599 and the discovery that it pulsates nonradially with at least 7 fre quencies between 27.01 and 38.11 cycles per day (312 to 441 mu Hz). Th ese results are based on 116.7 hours of photometric data obtained with the Whole Earth Telescope network. New uvby beta photometry implies t hat the star is unevolved and located near the observed hot border of the classical instability strip. We give arguments for interpreting th e pulsation periods in terms of low-order low-degree nonradial p-modes . Rotational m-mode splitting is likely. Few radial modes could also b e present. The rich modal content and unevolved state of CD-24 degrees 7599 emphasize its importance for delta Scuti star asteroseismology. We detect linear combination frequencies of the pulsation modes with t he highest photometric amplitudes and suggest they are not normal mode s excited by resonance.