Asteroseismology of Kepler Algol-type oscillating eclipsing binaries

Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, Metaxa & Vas. Pavlou St., 15236 Penteli, Athens, Greece
e-mail: alliakos@noa.gr

Received: 25 May 2017
Accepted: 26 July 2017

Abstract

Context. This research paper contains light curve modelling, spectroscopy, and detailed asteroseismic studies for four out of a total of five semi-detached eclipsing binaries with a δ Scuti component that have been detected to date through Kepler mission; these objects are KIC 06669809, KIC 10581918, KIC 10619109, and KIC 11175495.

Aims. The goal is to study the pulsational characteristics of the oscillating stars of the systems and to estimate their absolute parameters and enrich the, thus far, poor sample of such systems.

Methods. Ground-based spectroscopic observations provided the means to estimate the spectral types of the primary components and to model the light curves with higher certainty. The photometric data were analysed using eclipsing binary modelling techniques, while Fourier analysis was applied on their residuals to reveal the pulsation frequency modes.

Results. The results of analyses show that the primaries are pulsating stars of δ Scuti type and that all systems belong to the group of Algol-type binaries that have an oscillating star (oEA stars). The primaries of KIC 06669809, KIC 10581918, and KIC 10619109 pulsate in three, two, and five frequencies, respectively, and more than 200 others are detected as combination frequencies. The pulsator of KIC 11175495 is the youngest and fastest δ Scuti star that has ever been found in a binary system and oscillates in three main non-radial frequencies and in another 153 dependent frequencies. Moreover, comparisons of the properties of these binaries with other systems of the same type and with theoretical models of pulsating stars are also presented and discussed.