Meta-analysis of photometric and asteroseismic measurements of stellar rotation periods: the Lomb-Scargle periodogram, autocorrelation function, wavelet and rotational splitting analysis for 92 Kepler asteroseismic targets

TL;DR

This study compares photometric and asteroseismic methods for measuring stellar rotation periods in 92 Kepler stars, revealing that photometric periods often vary significantly and should be interpreted cautiously, especially with differential rotation.

Contribution

It provides a comprehensive comparison of photometric and asteroseismic rotation period measurements, highlighting the reliability issues and identifying promising targets for further study.

Findings

Most targets show significant quarter-to-quarter variance in photometric periods.

A subset of stars has consistent photometric and asteroseismic rotation periods.

Over ten stars exhibit significant discrepancies between the two measurement methods.

Abstract

We perform photometric (the Lomb-Scargle periodogram, autocorrelation, and wavelet) and asteroseismic analyses of 92 Kepler solar-like main-sequence stars to understand the reliability of the measured stellar rotation periods. We focus on the 70 stars without reported stellar companions, and classify them into four groups according to the quarter-to-quarter variance of the Lomb-Scargle period and the precision of the asteroseismic period. We present detailed individual comparison among photometric and asteroseismic constraints for these stars. We find that most of our targets exhibit significant quarter-to-quarter variances in the photometric periods, suggesting that the photometrically estimated period should be regarded as a simplified characterization of the true stellar rotation period, especially under the presence of the latitudinal differential rotation. On the other hand, there are a fraction of stars with a relatively small quarter-to-quarter variance in the photometric periods, most of which have consistent values for asteroseismically and photometrically estimated rotation periods. We also identify over ten stars whose photometric and asteroseismic periods significantly disagree, which would be potentially interesting targets for further individual investigations.