Frequency analysis of the hybrid δ Sct-γ Dor star CoRoT-102314644

Abstract

Context. Observations from space missions allowed significant progress due to the absence of atmospheric noise contributions and having uninterrupted data sets. This has been extremely beneficial in asteroseismology because many oscillation frequencies, not observable from the ground, can be detected. One example of this success is the large number of hybrid δ Sct-γ Dor stars discovered. These stars have radial and non-radial p and g modes simultaneously excited, allowing us to probe both the external and near-to-core layers. Aims. We aim to analyse the light curve of the hybrid δ Sct-γ Dor star CoRoT ID 102314644 and characterise its frequency spectrum. Using the detected frequencies, we intend to perform an initial interpretation developing stellar models. Methods. The frequency analysis was obtained with a classical Fourier analysis. A detailed analysis of the individual frequencies is performed using phase diagrams and other light curve characteristics. Initial stellar modelling was performed using the Cesam2k and the GYRE code. Results. We detected 29 γ Dor type frequencies in the [0.32 − 3.66] c/d range and a series of six equidistant periods with a mean period spacing of ΔΠ = 1612 s. In the δ Sct domain, we found 38 frequencies in the [8.63 − 24.73] c/d range and a quintuplet centred on the frequency p1 = 11.39 c/d, which suggests a rotational period of 3.06 d. The frequency analysis suggests the presence of spots. Nevertheless, we could not dismiss the possibility of a binary system. The initial modelling of the frequency data allowed us to refine its astrophysical parameters. Conclusions. The observed period spacing, a p-mode quintuplet, the possible rotation period, and the analysis of the individual frequencies impose significant constraints on our understanding of differential rotation and magnetic fields operating in A–F-type stars. Nevertheless, it is fundamental to accompany photometric data with spectroscopic measurements to distinguish variations between surface activity from a companion.