SEARCH FOR NEW PULSATING O-VI CENTRAL STARS OF PLANETARY-NEBULAE

A photoelectric monitoring program has been applied, during the last f our years, to five central stars of planetary nebulae (PNNs) with stro ng O VI lambda 3811-34 Angstrom emission. NGC6905 and, marginally, NGC 2452, show intrinsic luminosity variations, while NGC7026, IC2003 and NGC1501 have constant luminosity within a few mmag. Photometric data h ave been analyzed with the best available packages for power-spectra r eductions. Both pulsators have periods and physical characteristics we ll encompassed by the theoretical pulsational models relative to these stars.