The new Kepler picture of variability among A and F type stars

TL;DR

This study uses Kepler data to analyze variability in 750 A-F type stars, revealing insights into pulsation mechanisms and suggesting revisions to existing instability strip models based on detailed light curve observations.

Contribution

First comprehensive characterization of A-F star variability with Kepler data, exploring pulsation mechanisms and proposing updates to instability strip boundaries.

Findings

Identification of hybrid pulsators among A-F stars

Implications for pulsation driving mechanisms beyond traditional models

Potential revision of delta Scuti and gamma Doradus instability strips

Abstract

The Kepler spacecraft is providing photometric time series with micro-magnitude precision for thousands of variable stars. The continuous time-series of unprecedented time span open up opportunities to study the pulsational variability in much more detail than was previously possible from the ground. We present a first general characterization of the variability of A-F type stars as observed in the Kepler light curves of a sample of 750 candidate A-F type stars, and investigate the relation between gamma Doradus, delta Scuti, and hybrid stars. Our results imply an investigation of pulsation mechanisms to supplement the kappa mechanism and convective blocking effect to drive hybrid pulsations and suggest a revision of the current observational instability strips of delta Scuti and gamma Doradus stars if the currently available values of effective temperature and surface gravity will be confirmed.