On the period variability of GP andromedae

The present paper deals with the pulsation period variability of the high-amplitude δ Scuti star GP Andromedae using a data set covering a time base of 26.9 years. The possibility of a periodic component (reflecting the light-time effect induced by a hypothetic binarity) in the O-C curve is inferred. The presence of this periodicity in the period variation of GP And leads to a diminution of the discrepancy between predicted and observed relative period change rates. The hypothesis of the existence of an unseen companion is discussed. The statistical analysis of the final O-C residuals distribution, indicates their normal or close to normal character. This revised version was published online in July 2006 with corrections to the Cover Date.