Eclipsing binaries with pulsating components: CoRoT 102918586

TL;DR

This study analyzes the light curve of CoRoT 102918586, revealing multi-frequency pulsations in an eclipsing binary with a primary star likely a b Dor pulsator, combining photometry and spectroscopy.

Contribution

It introduces an iterative method to disentangle eclipses from pulsations and provides the first detailed frequency analysis of this binary system.

Findings

35 clear pulsation frequencies identified

Main pulsation frequency at 1.22 c/d consistent with b Dor variables

Most frequencies are interpreted as rotational splitting

Abstract

We present the preliminary results of the study of an interesting target in the first CoRoT exo-planet field (IRa1): CoRoT 102918586. Its light curve presents additional variability on the top of the eclipses, whose pattern suggests multi- frequency pulsations. The high accuracy CoRoT light curve was analyzed by applying an iterative scheme, devised to disentangle the effect of eclipses from the oscillatory pattern. In addition to the CoRoT photometry we obtained low resolution spectroscopy with the AAOmega multi-fiber facility at the Anglo Australian Observatory, which yielded a spectral classification as F0 V and allowed us to infer a value of the primary star effective temperature. The Fourier analysis of the residuals, after subtraction of the binary light curve, gave 35 clear frequencies. The highest amplitude frequency, of 1.22 c/d, is in the expected range for both \gamma Dor and SPB pulsators, but the spectral classification favors the first hypothesis. Apart from a few multiples of the orbital period, most frequencies can be interpreted as rotational splitting of the main frequency (an l = 2 mode) and of its overtones.