A Search for Random Cycle-to-Cycle Period Fluctuations in Five delta Scuti, SX Phoenicis, and RR Lyrae Variables

Volume 35 number 2 (2007)

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John R. Percy

Kaushala Bandara

Pietro Cimino

Department of Astronomy and Astrophysics, University of Toronto, Toronto ON

Abstract

Random cycle-to-cycle period fluctuations in pulsating stars were first studied by Eddington and Plakidis in 1929, and have subsequently been found in almost all Mira stars, many RV Tauri stars, and a few Cepheids. They complicate the use of (O-C) diagrams for studying evolutionary period changes in these stars. We set out to study such fluctuations in four δ Scuti stars and SX Phoenicis stars; we added one RR Lyrae star for testing purposes. We discuss complications that arise in applying this method to short-period stars. Only one of the five stars—the SX Phoenicis star XX Cyg—showed statistically-significant fluctuations.