Long rotation period main-sequence stars from Kepler SAP light curves

TL;DR

This study develops a systematic approach to detect long rotation periods in main-sequence stars using Kepler SAP light curves, overcoming artefacts to identify over 1000 stars with periods longer than 30 days, including 165 new discoveries.

Contribution

The paper introduces a novel method for analyzing SAP light curves to reliably detect long stellar rotation periods, addressing artefacts and validating results with photometry.

Findings

Identified over 1000 long-period main-sequence stars.

Discovered 165 new stars with rotation periods over 30 days.

Most detected periods are confirmed through photometric validation.

Abstract

Stellar rotation plays a key role in stellar activity. The rotation period could be detected through light curve variations caused by starspots. Kepler provides two types of light curves, one is the Pre-search Data Conditioning (PDC) light curves, the other is the Simple Aperture Photometer (SAP) light curves. Compared with the PDC light curves, the SAP light curves keep the long-term trend, relatively suitable for searches of long period signals. However, SAP data are inflicted by some artefacts such as quarterly rolls and instrumental errors, making it difficult to find the physical periods in the SAP light curves. We explore a systematic approach based on the light curve pre-processing, period detection and candidate selection. We also develop a simulated light curve test to estimate our detection limits for the SAP-like LCs. After applying our method to the raw SAP light curves, we found more than 1000 main-sequence stars with the period longer than 30 days, 165 are newly discovered. Considering the potential flaw of the SAP, we also inspect the newly found objects with photometry methods, and most of our periodical signals are confirmed.