Amplitude and frequency modulation of super-Nyquist frequency from Kepler photometric sampling

TL;DR

This paper demonstrates through simulation that super-Nyquist frequencies in Kepler data can exhibit apparent amplitude and frequency modulations caused by barycentric time corrections, affecting the interpretation of stellar pulsations.

Contribution

It reveals that barycentric time corrections induce observable modulations in super-Nyquist frequencies, a factor previously overlooked in Kepler data analysis.

Findings

Super-Nyquist frequencies can show periodic modulations due to barycentric corrections.

Modulations are caused by the variable Nyquist frequency over the spacecraft's orbit.

These effects are detectable in Kepler's photometric data of pulsating stars.

Abstract

We present a simulation showing that super-Nyquist frequencies may have periodic amplitude and frequency modulations, even if actually stable, in time series sampled like the Kepler data. These modulations are caused by the barycentric time correction, which destroys the evenly spaced time measurements, making the Nyquist frequency variable over the spacecraft orbit around the Sun. These modulations can easily be identified in pulsating stars from Kepler's photometric data.