KIC 4247791: A SB4 system with two eclipsing binaries (2EBs)

TL;DR

KIC 4247791 is a rare hierarchical quadruple star system composed of two eclipsing binaries, with spectral analysis revealing all components as F-type stars and explaining the light curve features.

Contribution

This study identifies KIC 4247791 as a rare SB4 system with two eclipsing binaries, clarifying the nature of its components and the origin of its light curve features.

Findings

KIC 4247791 is an SB4 star system with two eclipsing binaries.

All four components are spectral type F stars.

The shallow light curve dip is caused by the second binary's eclipses.

Abstract

KIC 4247791 is an eclipsing binary observed by the Kepler satellite mission. We wish to determine the nature of its components and in particular the origin of a shallow dip in its Kepler light curve that previous investigations have been unable to explain in a unique way. We analyze newly obtained high-resolution spectra of the star using synthetic spectra based on atmosphere models, derive the radial velocities of the stellar components from cross-correlation with a synthetic template, and calculate the orbital solution. We use the JKTEBOP program to model the Kepler light curve of KIC 4247791. We find KIC 4247791 to be a SB4 star. The radial velocity variations of its four components can be explained by two separate eclipsing binaries. In contradiction to previous photometric findings, we show that the observed composite spectrum as well as the derived masses of all four of its components correspond to spectral type F. The observed small dip in the light curve is not caused by a transit-like phenomenon but by the eclipses of the second binary system. We find evidence that KIC 4247791 might belong to the very rare hierarchical SB4 systems with two eclipsing binaries.