Apparent non-variable stars from the Kepler mission

TL;DR

This study identifies a large sample of non-variable stars in Kepler data, providing valuable calibration sources and testing grounds for pulsational models, by analyzing light curves across multiple frequency ranges.

Contribution

It introduces a systematic method to detect non-variable stars in Kepler data using frequency analysis and false-alarm probability thresholds, expanding the catalog of stable stars.

Findings

Identified 14,154 non-variable stars in Kepler data.

Defined three frequency ranges for variability assessment.

Used Lomb-Scargle periodogram and FAP to classify stars.

Abstract

The analysis of non-variable stars is generally neglected in the literature. However, such objects are needed for many calibration processes and for testing pulsational models. The photometric time series of the Kepler satellite mission still stand as the most accurate data available today and are excellently suited to the search for non-variable stars. We analysed all long-cadence light curves for stars not reported as a variable so far from the Kepler satellite mission. Using the known characteristics and flaws of these data sets, we defined three different frequency ranges where we searched for non-variability. We used the Lomb-Scargle periodogram and the false-alarm probability (FAP) to analyse the cleaned data sets of 138 451 light curves. We then used log FAP > -2 to define a star as "non-variable" in the ranges below 0.1 c/d, 0.1 to 2.0 c/d, and 2.0 to 25.0 c/d, respectively. Furthermore, we also calculated the standard deviation of the mean light curve to obtain another parameter. In total, we found 14 154 stars that fulfil the set