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

Abstract

Abstract. The γ 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 γ 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 γ Dor stars appear now as unique targets to explore internal angular momentum transport in the progenitors of red giants. Yet, the γ 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 γ Dor stars. We confirm their potential to explore the rotation history of this early phase of stellar evolution.

KIC 4142768: An Evolved Gamma Doradus/Delta Scuti Hybrid Pulsating Eclipsing Binary with Tidally Excited Oscillations

“…Thanks to the probing capability of g modes and mixed modes, an increasing number of stars have both the surface and near-core rotation rates measured (Salmon et al 2017;Aerts et al 2017Aerts et al , 2019. It reveals the angular momentum transfer history through the life of stars from the main-sequence to the giant branch.…”