The γ Dor stars as revealed by Kepler: A key to reveal deep-layer rotation in A and F stars

S J A J Salmon,R.-M Ouazzani,V Antoci,T R Bedding,S J Murphy

doi:10.1051/epjconf/201715205002

Abstract

The {\gamma} Dor pulsating stars present high-order gravity modes, which make them important targets in the intermediate-and low-mass main-sequence region of the Hertzsprung-Russell diagram. Whilst we have only access to rotation in the envelope of the Sun, the g modes of {\gamma} Dor stars can in principle deliver us constraints on the inner layers. With the puzzling discovery of unexpectedly low rotation rates in the core of red giants, the {\gamma} Dor stars appear now as unique targets to explore internal angular momentum transport in the progenitors of red giants. Yet, the {\gamma} Dor pulsations remain hard to detect from the ground for their periods are close to 1 day. While the CoRoT space mission first revealed intriguing frequency spectra, the almost uninterrupted 4-year photometry from the Kepler mission eventually shed a new light on them. It revealed regularities in the spectra, expected to bear signature of physical processes, including rotation, in the shear layers close to the convective core. We present here the first results of our effort to derive exploitable seismic diagnosis for mid- to fast rotators among {\gamma} Dor stars. We confirm their potential to explore the rotation history of this early phase of stellar evolution.

Highlights

In the last decade, asteroseismology has gathered in a wealth of results thanks, among others, to the CoRoT and Kepler space missions
We present and summarize the first results obtained on the internal rotation in γ Dor stars observed by Kepler
With the unprecedented quality and length of the Kepler data, we have access to the rotation of the deep layers in γ Dor stars

Summary

Introduction

Asteroseismology has gathered in a wealth of results thanks, among others, to the CoRoT and Kepler space missions. As e.g. angular momentum transport by internal gravity waves ([16]) or mixed modes ([5]), were suggested but appear insufficient to explain the low contrast of rotation between core and surface observed in red giants. These new results push for exploring the preceding phases of the evolution to bring additional constraints on the unknown mechanism. We conclude on how further investigation of these stars may pave the way to retrieve the evolution of rotation during the main sequence of intermediateand low-mass stars

Revealing the internal rotation of γ Dor stars

Conclusion