Tidally Induced Pulsations in Kepler Eclipsing Binary KIC 3230227

TL;DR

This study analyzes a highly eccentric eclipsing binary system, revealing tidally driven pulsations consistent with linear tidal theory, and provides detailed stellar parameters for the system.

Contribution

First detailed analysis of tidally induced pulsations in an eccentric eclipsing binary with comprehensive stellar characterization.

Findings

Pulsations are mostly integer multiples of orbital frequency.

Pulsation amplitudes and phases match linear tidal theory predictions.

System consists of two A-type stars with well-constrained masses and radii.

Abstract

KIC 3230227 is a short period ($P\approx 7.0$ days) eclipsing binary with a very eccentric orbit ($e=0.6$). From combined analysis of radial velocities and {\it Kepler} light curves, this system is found to be composed of two A-type stars, with masses of $M_1=1.84\pm 0.18M_{\odot}$, $M_2=1.73\pm 0.17M_{\odot}$ and radii of $R_1=2.01\pm 0.09R_{\odot}$, $R_2=1.68\pm 0.08 R_{\odot}$ for the primary and secondary, respectively. In addition to an eclipse, the binary light curve shows a brightening and dimming near periastron, making this a somewhat rare eclipsing heartbeat star system. After removing the binary light curve model, more than ten pulsational frequencies are present in the Fourier spectrum of the residuals, and most of them are integer multiples of the orbital frequency. These pulsations are tidally driven, and both the amplitudes and phases are in agreement with predictions from linear tidal theory for $l=2, m=-2$ prograde modes.