Delta Scuti Stars in Stellar Systems: the interest of HD 220392 and HD 220391

The very wide double star CCDM 23239-5349 is an interesting study case of apulsating star within a common origin pair or wide binary. Both stars arelocated in the Delta Scuti instability strip. Based on data obtained at LaSilla (Chile), at the Swiss 0.7m and the ESO 0.5m telescopes, we found twoperiodicities of about 4.7 and 5.5 cycles per day (cpd) with amplitudes of0.014 and 0.011 mag, respectively, for HD 220392, the brightest member of thesystem. The most dominant periodicity was also detected in the Hipparcos EpochPhotometry data. A similar period search on the (smaller) dataset obtained forthe 1 mag fainter B-component, HD 220391, however shows no periodic behaviourwith an amplitude significantly above the noise level of the data (about 0.006mag)