How stable are our standard candles? Time-resolved analysis of amplitude and period changes in OGLE-III LMC Cepheids

Abstract

AbstractWe revisit a group of OGLE-III Cepheids that exhibit nearby double peaks in their periodograms using a technique of statistics called kernel modelling. We investigate the phenomenology of these Cepheids (termed twin-peak Cepheids in this paper) in more detail by comparing a sample of 29 LMC Cepheids that exhibit twin frequency peaks with 24 other Cepheids that do not. Using the kernel technique, we investigate light curve variability as a function of time, revealing both frequency and amplitude modulations. We present the preliminary results of our study in progress, which suggests a complex interplay between the two types of modulations and their detectability via twin peaks in the periodogram. The study reveals the potential of the kernel technique to help theory and modelling with detailed data analyses, capable of tracing fine time-dependent variations of the phenomenology of pulsations for objects of surveys or observation campaigns producing sufficiently dense time sampling.