Eclipse Timing Variations of Planets in P-Type Binary Star Systems (original) (raw)
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Monthly Notices of the Royal Astronomical Society, 2011
In close eclipsing binaries, measurements of the variations in binary's eclipse timing may be used to infer information about the existence of circumbinary objects. To determine the possibility of the detection of such variations with CoRoT and Kepler space telescopes, we have carried out an extensive study of the dynamics of a binary star system with a circumbinary planet, and calculated its eclipse timing variations (ETV) for different values of the mass-ratio and orbital elements of the binary and the perturbing body. Here, we present the results of our study and assess the detectability of the planet by comparing the resulting values of ETVs with the temporal sensitivity of CoRoT and Kepler. Results point to extended regions in the parameter-space where the perturbation of a planet may become large enough to create measurable variations in the eclipse timing of the secondary star. Many of these variations point to potentially detectable ETVs and the possible existence of Jovian-type planets.
Eclipse timing variations to detect possible Trojan planets in binary systems
Monthly Notices of the Royal Astronomical Society, 2015
This paper is devoted to study the circumstances favourable to detect Trojan planets in close binary-star-systems by the help of eclipse timing variations (ETVs). To determine the probability of the detection of such variations with ground based telescopes and space telescopes (like former missions CoRoT and Kepler and future space missions like Plato, Tess and Cheops), we investigated the dynamics of binary star systems with a planet in tadpole motion. We did numerical simulations by using the full threebody problem as dynamical model. The stability and the ETVs are investigated by computing stability/ETV maps for different masses of the secondary star and the Trojan planet. In addition we changed the eccentricity of the possible Trojan planet. By the help of the libration amplitude σ we could show whether or not all stable objects are moving in tadpole orbits. We can conclude that many amplitudes of ETVs are large enough to detect Earth-like Trojan planets in binary star systems. As an application, we prepared a list of possible candidates.
arXiv (Cornell University), 2019
Eclipse time variations have been detected in a number of post common envelope binary systems consisting of a subdwarf B star or white dwarf primary star and cool M type or brown dwarf secondary. In this paper we consider circumbinary hypotheses of two sdB systems, HS 0705+6700 (also known as V470 Cam) and NSVS 14256825 and one white dwarf system, NN Ser. In addition, and for comparison purposes, we investigate the eclipse time variations of the W UMa system NSVS 01286630 with its stellar circumbinary companion. All four systems have claims of circumbinary objects with computed physical and orbital parameters. We report 108 new observations of minima for these four eclipsing systems observed between 2017 May and 2019 September and combining these with all published data, we investigate how well the published circumbinary object hypotheses fit with our new data. Our new data has shown departure from early predictions for three of the four systems, but it is premature to conclude that these results rule out the presence of circumbinary objects. There is also the possibility (but with no observational proof so far) of detecting close-in transiting circumbinary objects around these systems but these are likely to have periods of days rather than years.
A comprehensive study of the Kepler triples via eclipse timing
Monthly Notices of the Royal Astronomical Society, 2015
We produce and analyze eclipse time variation (ETV) curves for some 2600 targeted main-field Kepler binaries. We find good to excellent evidence for a third body in 222 systems via either the light-travel-time (LTTE) or dynamical effect delays. Approximately half of these systems have been discussed in previous work, while the rest are newly reported here. Via detailed analysis of the ETV curves using high-level analytic approximations, we are able to extract system masses and information about the three-dimensional characteristics of the triple for 62 systems which exhibit both LTTE and dynamical delays. For the remaining 160 systems whose ETV curves are dominated by LTTE delays we are able to extract the outer orbital period, eccentricity, and longitude of periastron as well as the mass function of the triple. In general, our solutions improve upon those published earlier. New techniques of preprocessing the flux time series are applied to eliminate false positive triples and to enhance the ETV curves. The set of triples with outer orbital periods shorter than ∼2000 days is now sufficiently numerous for meaningful statistical analysis. We find that (i) as predicted, there is a peak near i m 40 • in the distribution of the triple vs. inner binary mutual inclination angles that provides strong confirmation of the operation of Kozai-Lidov cycles with tidal friction; (ii) the median eccentricity of the third-body orbits is e 2 = 0.35; (iii) there is a deficit of triple systems with binary periods 1 day and outer periods between ∼50 and 200 days which might help guide the refinement of theories of the formation and evolution of close binaries; and (iv) the substantial fraction of Kepler binaries which have third-body companions is consistent with a very large fraction of all binaries being part of triples.
The detectability of binary star planetary and brown dwarf companions from eclipse timing variations
Monthly Notices of the Royal Astronomical Society, 2021
In this paper, we determine the detectability of eclipsing binary star companions from eclipse timing variations using the Kepler mission dataset. Extensive and precise stellar time-series photometry from space-based missions enable searches for binary star companions. However, due to the large datasets and computational resources involved, these searches would benefit from guidance from detection simulations. Our simulations start with and benefit from the use of empirical Kepler mission data, into which we inject third bodies to predict the resulting timing of binary star eclipses. We find that the orbital eccentricity of the third body and the orbital period of the host binary star are the key factors in detecting companions. Target brightness is also likely to be a factor in detecting companions. Detectable third body masses and periods can be efficiently bound using just two equations. Our results enable the setting of realistic expectations when planning searches for eclipsing binary star planetary and brown dwarf companions. Our results also suggest the brown dwarf desert is real rather than observational selection.
Monthly Notices of the Royal Astronomical Society, 2020
Eclipse timing variation analysis has become a powerful method to discover planets around binary systems. We applied this technique to investigate the eclipse times of GK Vir. This system is a post-common envelope binary with an orbital period of 8.26 h. Here, we present 10 new eclipse times obtained between 2013 and 2020. We calculated the O−C diagram using a linear ephemeris and verified a clear orbital period variation (OPV) with a cyclic behaviour. We investigated if this variation could be explained by the Applegate mechanism, the apsidal motion, or the light travel time (LTT) effect. We found that the Applegate mechanism would hardly explain the OPV with its current theoretical description. We obtained using different approaches that the apsidal motion is a less likely explanation than the LTT effect. We showed that the LTT effect with one circumbinary body is the most likely cause for the OPV, which was reinforced by the orbital stability of the third body. The LTT best solut...
The Astrophysical Journal, 2013
We report on a study of eclipse timing variations in contact binary systems, using long-cadence lightcurves in the Kepler archive. As a first step, 'observed minus calculated' (O − C) curves were produced for both the primary and secondary eclipses of some 2000 Kepler binaries. We find ∼390 shortperiod binaries with O − C curves that exhibit (i) random-walk like variations or quasi-periodicities, with typical amplitudes of ±200-300 seconds, and (ii) anticorrelations between the primary and secondary eclipse timing variations. We present a detailed analysis and results for 32 of these binaries with orbital periods in the range of 0.35 ± 0.05 days. The anticorrelations observed in their O − C curves cannot be explained by a model involving mass transfer, which among other things requires implausibly high rates of ∼0.01 M ⊙ yr −1. We show that the anticorrelated behavior, the amplitude of the O − C delays, and the overall random-walk like behavior can be explained by the presence of a starspot that is continuously visible around the orbit and slowly changes its longitude on timescales of weeks to months. The quasi-periods of ∼50 − 200 days observed in the O − C curves suggest values for k, the coefficient of the latitude dependence of the stellar differential rotation, of ∼0.003−0.013.
The Astrophysical Journal, 2014
KOI-227, KOI-319 and KOI-884 are identified here as (at least) two planet systems. For KOI-319 and KOI-884, the observed Transit Timing Variations (TTVs) of the inner transiting planet are used to detect an outer non-transiting planet. The outer planet in KOI-884 is ≃2.6 Jupiter masses and has the orbital period just narrow of the 3:1 resonance with the inner planet (orbital period ratio 2.93). The distribution of parameters inferred from KOI-319.01's TTVs is bimodal with either a ≃1.6 Neptune-mass (M N ) planet wide of the 5:3 resonance (period 80.1 d) or a ≃1 Saturn-mass planet wide of the 7:3 resonance (period 109.2 d). The radial velocity measurements can be used in this case to determine which of these parameter modes is correct. KOI-227.01's TTVs with large ≃10 hour amplitude can be obtained for planetary-mass companions in various major resonances. Based on the Bayesian evidence, the current TTV data favor the outer 2:1 resonance with a companion mass ≃1.5 M N , but this solution implies a very large density of KOI-227.01. The inner and outer 3:2 resonance solutions with sub-Neptune-mass companions are physically more plausible, but will need to be verified.
Variations of The Transit Timing of Planets in Binary Star Systems
2010
We have carried out numerical calculations of the variations of the transit timing of a close-in giant planet in a binary star system. To determine whether the TTV method is capable of detecting transiting extrasolar planets in binary systems, we calculated TTV signals for different values of the mass-ratio and orbital elements of a binary and its transiting circumprimary planet. Results suggest that TTV signals in the currently known close planet-hosting binaries are small. However, there are regions of the parameter-space where the perturbation of the secondary star may become large enough to create measurable variations in the transit timing of a closein planet. We present the result of our study and discuss their applicability to the detection of planets in binary stars systems using CoRoT and Kepler space telescopes.
The Dwarf project: Eclipsing binaries - precise clocks to discover exoplanets
We present a new observational campaign, Dwarf, aimed at detection of circumbinary extrasolar planets using the timing of the minima of low-mass eclipsing binaries. The observations will be performed within an extensive network of relatively small to medium-size telescopes with apertures of ∼20-200 cm. The starting sample of the objects to be monitored contains (i) low-mass eclipsing binaries with M and K components, (ii) short-period binaries with a sdB or sdO component, and (iii) post-common-envelope systems containing a WD, which enable to determine minima with high precision. Since the amplitude of the timing signal increases with the orbital period of an invisible third component, the timescale of the project is long, at least 5-10 years. The paper gives simple formulas to estimate the suitability of individual eclipsing binaries for the circumbinary planet detection. Intrinsic variability of the binaries (photospheric spots, flares, pulsation etc.) limiting the accuracy of the minima timing is also discussed. The manuscript also describes the best observing strategy and methods to detect cyclic timing variability in the minima times indicating the presence of circumbinary planets. First test observations of the selected targets are presented.