KIC 7914906: An Eclipsing Heartbeat Star with Tidally Excited Oscillations and Gamma Doradus/Delta Scuti Hybrid Pulsations

TL;DR

This paper studies the eclipsing Heartbeat Star KIC 9704906, revealing tidally excited oscillations and hybrid pulsations, with detailed orbital and stellar parameters, and identifying multiple pulsation modes and their possible origins.

Contribution

It provides the first detailed analysis of TEOs and hybrid pulsations in KIC 9704906, including mode identification and orbital characterization, expanding understanding of pulsations in eccentric binary systems.

Findings

Eight TEO candidates consistent with spherical harmonic modes.

Identification of ten independent pulsation frequency candidates.

Rotation period of one component estimated at 11.52 days.

Abstract

We present the eclipsing Heartbeat Star KIC 9704906 with tidally excited oscillations (TEOs) and gamma Doradus/delta Scuti hybrid pulsations. The derived parameters show that it has an orbital period of $P$=8.7529108(1) days, a high eccentricity of $e$=0.467(3), and a high inclination of $i$=78$^{\circ}$.81(6). The mass ratio $q$=0.981(5), the relative radii (radius divided by semi-major axis) $r_1$=0.0639(2), and $r_2$=0.0715(4) indicate that the secondary component has a less mass and a larger radius, and may have evolved off the main sequence. The eight derived TEO candidates, $n$ = 3, 4, 5, 6, 7, 12, 40, and 44 harmonics, are consistent with or close to the dominant spherical harmonic $l=2$, $m=0$, or $\pm2$, assuming that the spin and orbital axes are aligned, and the pulsations are adiabatic and standing waves. We also identify ten independent frequency candidates, but one of them, $\mathit{f_{7}}$, is more like a modulation of a quasi-periodic signal and the orbits. According to the g-mode frequencies, we find that the rotation period of one component is 11.52(29) days. Although the masses and radii cannot be further constrained due to the lack of sufficient high-precision spectra, the fascinating phenomena in the Fourier spectra are evident and valuable in this system.