Pyriod: Prewhitening Package for Asteroseismology
Abstract
Pyriod is an interactive Python package designed for analyzing light curves of pulsating variable stars for asteroseismology. Pyriod implements the pre-whitening algorithm to obtain a sum-of-sinusoids fit to the light curve, where significant frequencies of sinusoidal variations are identified in a periodogram and then fit to the time series data. Frequency solutions are built up by iteratively identifying new signals in the periodogram of the fit residuals until no significant signals remain. This yields a set of measured signal frequencies, amplitudes, and phases, with their uncertainties. Pyriod provides a GUI that embeds in Jupyter notebooks for interactive data analysis, though its functions can also be called programmatically for automated analysis. Pyriod provides similar functionality as Period04, but it performs substantially faster for long TESS/Kepler time series. Pyriod models harmonics and combination frequencies arithmetically, and we show how it can be used to construct O-C diagrams to track phase-variable signals. The open-source code and tutorials can be accessed at https://github.com/keatonb/Pyriod/.