Kepler Mission Stellar and Instrument Noise Properties Revisited

TL;DR

This study revisits Kepler Mission noise properties over four years, showing modest improvements in instrument noise reduction and revealing that stellar noise, especially in solar-type stars, is lower than previously thought.

Contribution

It extends previous noise analysis to the full Kepler dataset and longer time scales, highlighting changes in instrument noise and consistent stellar noise levels.

Findings

Instrument noise reduced modestly with pipeline improvements.

Stellar noise levels remain consistent over time.

Solar-type stars show decreased stellar noise on longer time scales.

Abstract

An earlier study of the Kepler Mission noise properties on time scales of primary relevance to detection of exoplanet transits found that higher than expected noise followed to a large extent from the stars, rather than instrument or data analysis performance. The earlier study over the first six quarters of Kepler data is extended to the full four years ultimately comprising the mission. Efforts to improve the pipeline data analysis have been successful in reducing noise levels modestly as evidenced by smaller values derived from the current data products. The new analyses of noise properties on transit time scales show significant changes in the component attributed to instrument and data analysis, with essentially no change in the inferred stellar noise. We also extend the analyses to time scales of several days, instead of several hours to better sample stellar noise that follows from magnetic activity. On the longer time scale there is a shift in stellar noise for solar-type stars to smaller values in comparison to solar values.