THE ANTICORRELATED NATURE OF THE PRIMARY AND SECONDARY ECLIPSE TIMING VARIATIONS FOR THE<i>KEPLER</i>CONTACT BINARIES

We report the discovery of two new low-mass, thermally bloated, hot white dwarfs among the Kepler sample of eclipsing binaries. These are KIC 9164561 and KIC 10727668 with orbital periods of 1.2670 and 2.3058 days, respectively. The current primary in both systems is an A star of about 2  M . This brings the number of similar binaries among the Kepler sample to six, and the two new systems have the shortest orbital periods among them. The white dwarf (WD) in KIC 9164561 has the largest thermal bloating, compared to its cold degenerate radius, of about a factor of 14. We utilize radial velocity measurements of the A star in KIC 9164561 to determine the WD mass rather accurately:. The mass of the WD in KIC 10727668 is based on the Doppler boosting signal in the Kepler photometry and is less accurately determined to be . Based on the inferred radii and effective temperatures of these two white dwarfs, we are able to make an independent theoretical estimate of their masses to within ∼0.01  M based on evolutionary models of their cooling history after they lose their hydrogen-rich envelopes. We also present evidence that there is a third body in the KIC 9164561 system with an orbital period of 8-14 yr.

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“…Some of the results have been reported elsewhere Tran et al 2013). The O-C curve for KIC 9164561 is discussed in Section 9.…”

Section: Data Preparation and Searchmentioning

confidence: 96%

DISCOVERY OF TWO NEW THERMALLY BLOATED LOW-MASS WHITE DWARFS AMONG THEKEPLERBINARIES

Rappaport

Nelson

Levine

et al. 2015

ApJ

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“…The ∆Q values are found less than 10 51 gr cm 2 for both systems, thus, according to the criterion of Lanza & Rodonò (2002), the magnetic activity cannot stand as possible explanation for the cyclic changes of their orbital periods. However, it should to be noted that the amplitudes of the periodic terms of the ETV fitting functions are quite small (∼ 0.0014 d and ∼ 0.0021 d for KIC 066 and KIC 105, respectively) and given that the secondary components are magnetically active stars, these cyclic variations of the P orb could be caused due to the spot's visibility (Kalimeris et al 2002;Tran et al 2013). The ETV diagrams of KIC 106 and KIC 111 (Conroy et al 2014;Gies et al 2015) seem that cannot provide any other useful information for the systems so far, except for some irregularities probably due to the presence of pulsations and spots.…”

Section: −1mentioning

confidence: 99%

Asteroseismology ofKeplerAlgol-type oscillating eclipsing binaries

Liakos

2017

A&A

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Context. This research paper contains light curve modelling, spectroscopy and detailed asteroseismic studies for four out of five in total semidetached eclipsing binaries with a δ Scuti component, that have been detected to date through Kepler mission, namely 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 as well as to estimate their absolute parameters and enrich the so far poor sample of this kind of systems. Methods. Ground based spectroscopic observations provide the means to estimate the spectral types of the primary components and to model the light curves with higher certainty. The photometric data are analysed using eclipsing binary modeling techniques, while Fourier analysis is applied on their residuals in order 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 with an oscillating star, namely oEA stars. The primaries of KIC 06669809, KIC 10581918, and KIC 10619109 pulsate in three, two, and five frequencies, respectively and in more than 200 other detected as combinations. The δ Scuti star of KIC 11175495 is the youngest and the fastest pulsator in binary systems that has ever been found and it oscillates in three main nonradial frequencies, while other 153 are also found as depended ones. Moreover, a comparison of their properties with other systems of the same type as well as with theoretical models of pulsating stars are also presented and discussed.

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“…The final column includes the code ECC to identify those systems with a non-zero eccentricity as indicated by significantly differing epochs of eclipse, The variations due to starspots are often found only in the timings for the eclipse of the cooler secondary component (for example, KIC 10581918 = WX Dra, an Algol-type binary; Figure 1.35). These variations are caused by the change in the surface intensity and center of light over the visible hemisphere (Kalimeris et al 2002;Tran et al 2013). For example, suppose a dark spot group rotates into view on the approaching portion of the eclipsed star.…”

Section: Eclipse Timing Measurementsmentioning

confidence: 99%

KEPLERECLIPSING BINARIES WITH STELLAR COMPANIONS

Gies

Matson

Guo

et al. 2015

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Many short-period binary stars have distant orbiting companions that have played a role in driving the binary components into close separation. Indirect detection of a tertiary star is possible by measuring apparent changes in eclipse times of eclipsing binaries as the binary orbits the common center of mass. Here we present an analysis of the eclipse timings of 41 eclipsing binaries observed throughout the NASA Kepler mission of long duration and precise photometry. This subset of binaries is characterized by relatively deep and frequent eclipses of both stellar components. We present preliminary orbital elements for seven probable triple stars among this sample, and we discuss apparent period changes in seven additional eclipsing binaries that may be related to motion about a tertiary in a long period orbit. The results will be used in ongoing investigations of the spectra and light curves of these binaries for further evidence of the presence of third stars.

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THE ANTICORRELATED NATURE OF THE PRIMARY AND SECONDARY ECLIPSE TIMING VARIATIONS FOR THEKEPLERCONTACT BINARIES

Cited by 94 publications

References 58 publications

DISCOVERY OF TWO NEW THERMALLY BLOATED LOW-MASS WHITE DWARFS AMONG THEKEPLERBINARIES

DISCOVERY OF TWO NEW THERMALLY BLOATED LOW-MASS WHITE DWARFS AMONG THEKEPLERBINARIES

Asteroseismology ofKeplerAlgol-type oscillating eclipsing binaries

KEPLERECLIPSING BINARIES WITH STELLAR COMPANIONS

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