Pulsating Spectrum of Subdwarf Star PG 1605+072: Comparative Time-Frequency Analysis via Wavelet Packet and Local Sine Packet Transforms of an Interrupted Light Curve

Abstract

We present the time-frequency analysis of an interrupted light-curve time series of the pulsating subdwarf B (sdB) star PG 1605+072. From the data of a eight-night observational run we have determined the pulsating spectrum of PG 1605+072. We used both wavelet packet transform (WPTs) and localized sine packet transform (LSPTs) analysis to compare frequency determinations with previous results based on Fourier methods and their typical modeling of signals by strictly harmonic contributions. The procedures adopted here allow the determination of the pulsating spectrum of the combined night runs of data with a reduction of the usual alias peaks produced by the daytime observing gaps, thus providing a clean and compact spectrum. We also use various compression techniques to study signal reconstruction under WPT.