THEKEPLERECLIPSING SYSTEM KIC 5621294 AND ITS SUBSTELLAR COMPANION

Abstract

We present the physical properties of KIC 5621294 showing light and timing variations from the Kepler photometry. Its light curve displays partial eclipses and O'Connell effect with Max II fainter than Max I, which was fitted quite well by applying third-body and spot effects to the system. The results indicate that the eclipsing pair is a classical Algol-type system with parameters of q=0.22, i=76 • .8, and ∆(T 1 -T 2 )=4,235 K, in which the detached primary component fills about 77% of its limiting lobe. Striking discrepancies exist between the primary and secondary eclipse times obtained with the method of Kwee & van Woerden. These are mainly caused by surface inhomogeneities due to spot activity detected in our light-curve synthesis. The 1,253 light-curve timings from the Wilson-Devinney code were used for a period study. It was found that the orbital period of KIC 5621294 has varied due to a periodic variation overlaid on a downward parabola. The sinusoidal variation with a period of 961 d and a semi-amplitude of 22.5 s most likely arise from a light-time effect due to a third component with a mass of M 3 sin i 3 =46.9 M Jup , which is in good agreement with that calculated from the light curve itself. If its orbital inclination is larger than about 40 • , the mass of the circumbinary object would possibly match a brown dwarf. The parabolic variation could not be fully explained by either a mass transfer between the binary components or an angular momentum via magnetic braking. It is possible that the parabola may only be the observed part of a period modulation caused by the presence of another companion in a wider orbit.

A comprehensive study of theKeplertriples via eclipse timing

“…The very questionable nature of the combined quadratic and low-amplitude LTTE solution given for KIC 05621294 was discussed above in Section 6.1. In addition, for KIC 05621294, after the application of the smoothing polynomials, the ETVs were found to be very low in amplitude and even significantly smaller than those of the low-amplitude solutions of both Zasche et al (2015) and Lee et al (2015). For KIC 03440230, our smoothed O − C curves, especially for the primary eclipse (see Fig.…”

Apsidal Motion Study of Close Binary System CW Cephei

“…It would very necessary to check whether our solution is globally valid for all parameter space. In line with this validity, we subsequently attempted a Monte Carlo simulation to obtain optimized values of the param both of the apsidal motion and the LTE orbit as performed by Lee et al (2015). After 800 simulations apsidal motion parameters showed a quick convergence to nearly the same values listed in Table 2, wh LTE parameters show relatively wide variation as shown in the histograms of Fig.…”

The Varying Light Curve and Timings of the Ultra-short Period Contact Binary KIC 9532219

“…For this purpose, the mean light level at phase 0.75 was set to unity. The light-curve synthesis was performed in a manner identical to that for the eclipsing systems V404 Lyr (Lee et al 2014) and KIC 5621294 (Lee et al 2015) exhibiting LTT effects. The effective temperature of the more massive star was set to be 5,031 K from the Kepler Input Catalogue (KIC; Kepler Mission Team 2009).…”

“…Times of minimum lights could be shifted from the real conjunctions due to asymmetrical eclipse minima originating from starspot activity (cf. Lee et al 2015). The light-curve synthesis method developed by W-D can gives more and better information with respect to other methods (Maceroni & van't Veer 1994).…”