Detection of Tidally Excited Oscillations in Kepler Heartbeat Stars

TL;DR

This study analyzes tidally excited oscillations in Kepler heartbeat stars, revealing correlations with orbital parameters and temperature, and providing new insights into tidal effects in eccentric binary systems.

Contribution

The paper introduces a novel analysis of TEOs in Kepler HBSs using improved modeling and a set of analytic procedures, analyzing 21 stars and highlighting key correlations.

Findings

12 HBSs show prominent TEOs with high S/N ratios

Positive correlation between orbital eccentricity and harmonic number of TEOs

TEOs are more visible in hot stars with T ≥ 6500 K

Abstract

Heartbeat stars (HBSs) with tidally excited oscillations (TEOs) are ideal laboratories for studying the effect of equilibrium and dynamical tides. However, studies of TEOs in Kepler HBSs are rare due to the need for better modeling of the equilibrium tide in light curves. We revisit the HBSs in our previous work and study the TEOs in these HBSs based on the derived orbital parameters that could express the equilibrium tide. We also compile a set of analytic procedures to examine the harmonic and anharmonic TEOs in their Fourier spectra. The TEOs of 21 HBSs have been newly analyzed and presented. Twelve of these HBSs show prominent TEOs (signal-to-noise ratio of the harmonics $S/N \ge 10$). The relation between the orbital eccentricities and the harmonic number of the TEOs shows a positive correlation. The relation between the orbital periods and the harmonic number also shows a positive correlation. Furthermore, the distribution of HBSs with TEOs in the Hertzsprung-Russell (H-R) diagram shows that TEOs are more visible in hot stars with surface effective temperatures $T$ $\gtrsim$ 6500 K. These samples may also be valuable targets for future studies of the effect of tidal action in eccentric orbits.