Echelle diagrams and period spacings of g modes in gamma Doradus stars from four years of Kepler observations

TL;DR

This study analyzes four years of Kepler data to examine g-mode oscillations in gamma Doradus stars, revealing regular period spacings, rotational effects, and chemical composition gradients, advancing asteroseismology in these stars.

Contribution

It demonstrates the use of period echelle diagrams to measure period spacings and identify rotationally split modes in gamma Doradus stars, showing potential for detailed asteroseismic analysis.

Findings

Identification of clear g-mode sequences

Detection of rotationally split multiplets

Observation of chemical composition gradient effects

Abstract

We use photometry from the Kepler Mission to study oscillations in gamma Doradus stars. Some stars show remarkably clear sequences of g modes and we use period echelle 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 gamma Dor stars.