Échelle diagrams and period spacings of g modes in γ Doradus stars from four years of Kepler observations

Abstract

We use photometry from the Kepler Mission to study oscillations in γ Do radus stars. Some stars show remarkably clear sequences of g modes and we use period échelle diagrams to measure period spacings and identify rotationally split multiplets with ℓ = 1 and ℓ = 2. We find small deviations from regular period spacings that arise from the gradient in the chemical composition just outside the convective core. We also find stars for which the period spacing shows a strong linear trend as a function of period, consistent with relatively rapid rotation. Overall, the results indicate it will be possible to apply asteroseismology to a range of γ Dor stars.