G. Maciejewski, M. Fernández, F. J. Aceituno, J. Ohlert, D. Puchalski, D. Dimitrov, M. Seeliger, M. Kitze, St. Raetz, R. Errman, H. Gilbert, A. Pannicke, J. -G.… 展开作者
G. Maciejewski, M. Fernández, F. J. Aceituno, J. Ohlert, D. Puchalski, D. Dimitrov, M. Seeliger, M. Kitze, St. Raetz, R. Errman, H. Gilbert, A. Pannicke, J. -G. Schmidt, R. Neuhäuser
The transiting hot Jupiter planet Qatar-1 b was presented to exhibit variations in transit times that could be of perturbative nature. A hot Jupiter with a planetary companion on a nearby orbit would constitute an unprecedented planetary configuration, important for theories of formation and evolution of planetary systems. We performed a photometric follow-up campaign to confirm or refute transit timing variations. We extend the baseline of transit observations by acquiring 18 new transit light curves acquired with 0.6-2.0 m telescopes. These photometric time series, together with data available in the literature, were analyzed in a homogenous way to derive reliable transit parameters and their uncertainties. We show that the dataset of transit times is consistent with a linear ephemeris leaving no hint for any periodic variations with a range of 1 min. We find no compelling evidence for the existence of a close-in planetary companion to Qatar-1 b. This finding is in line with a paradigm that hot Jupiters are not components of compact multi-planetary systems. Based on dynamical simulations, we place tighter constraints on a mass of any fictitious nearby planet in the system. Furthermore, new transit light curves allowed us to redetermine system parameters with the precision better than that reported in previous studies. Our values generally agree with previous determinations.
Variations in the timing of transiting exoplanets provide a powerful tool detecting additional planets in the system. Thus, the aim of this paper is to discuss the plausibility of transit timing variations on the Qatar-1 system by means of primary transit light curves analysis. Furthermore, we provide an interpretation of the timing variation. We observed Qatar-1 between March 2011 and October 2012 using the 1.2 m OLT telescope in Germany and the 0.6 m PTST telescope in Spain. We present 26 primary transits of the hot Jupiter Qatar-1b. In total, our light curves cover a baseline of 18 months. …
WASP-12b and Qatar-1b are transiting Hot Jupiters for which previous works have suggested the presence of transit timing variations (TTVs) indicative of additional bodies in these systems - an Earth-mass planet in WASP-12 and a brown-dwarf mass object in Qatar-1. Here, we present 23 new WASP-12b and 18 new Qatar-1b complete (or nearly complete) transit observations. We perform global system fits to all of our light curves for each system, plus RV and stellar spectroscopic parameters from the literature. The global fits provide refined system parameters and uncertainties for each system, includ…
New photometric follow-up observations of exoplanet transits of 'hot Jupiters' TrES-3b and Qatar-1b are presented. Weighted mean values of the solutions of light curves in R-fiter for both planetary systems are reported and compared with the previous results. The transit light curves were analysed using the WINFITTER code. The physical properties of the planets were estimated. The planet radii are found to be $R_p = 1.381 \pm 0.033 R_J$ for TrES-3b and $R_p = 1.142 \pm 0.025 R_J$ for Qatar-1b. Transit times and their uncertainties were also determined and a new linear ephemeris was computed fo…
We report the discovery of Qatar-3b, Qatar-4b, and Qatar-5b, three new transiting planets identified by the Qatar Exoplanet Survey (QES). The three planets belong to the hot Jupiter family, with orbital periods of $P_{Q3b}$=2.50792 days, $P_{Q4b}$=1.80539 days, and $P_{Q5b}$=2.87923 days. Follow-up spectroscopic observations reveal the masses of the planets to be $M_{Q3b}$=4.31$\pm0.47$ $M_{\rm J}$, $M_{Q4b}$=6.10$ \pm0.54$ $M_{\rm J}$, and $M_{Q5b}$ = 4.32$ \pm0.18$ $M_{\rm J}$, while model fits to the transit light curves yield radii of $R_{Q3b}$ = 1.096$ \pm0.14$ $R_{\rm J}$, $R_{Q4b}$ = 1.…
We present and analyze 58 transit light curves of TrES-3b and 98 transit light curves of Qatar-1b observed by Transiting Exoplanet Survey Satellite (TESS), plus two transit light curves of Qatar-1b observed by us using a ground-based 1.23\,m telescope. These light curves are combined with the best-quality light curves taken from the Exoplanet Transit Database (ETD) and literature. The precisely determined mid-transit times from these light curves enable us to obtain the refined orbital ephemerides with improved precision for both hot Jupiters. From the timing analysis, we find an indication fo…
We report the results of the transit timing variation (TTV) analysis of the extra-solar planet Qatar-1b using thirty eight light curves. Our analysis combines thirty five previously available transit light curves with three new transits observed by us between June 2016 and September 2016 using the 2-m Himalayan Chandra Telescope (HCT) at the Indian Astronomical Observatory (Hanle, India). From these transit data, the physical and orbital parameters of the Qatar-1 system are determined. In addition to this, the ephemeris for the orbital period and mid-transit time are refined to investigate the…
We report the discovery and initial characterization of Qatar-2b, a hot Jupiter transiting a V = 13.3 mag K dwarf in a circular orbit with a short period, P_ b = 1.34 days. The mass and radius of Qatar-2b are M_p = 2.49 M_j and R_p = 1.14 R_j, respectively. Radial-velocity monitoring of Qatar-2 over a span of 153 days revealed the presence of a second companion in an outer orbit. The Systemic Console yielded plausible orbits for the outer companion, with periods on the order of a year and a companion mass of at least several M_j. Thus Qatar-2 joins the short but growing list of systems with a …
Motivated by the unsettled conclusion on whether there are any transit timing variations (TTVs) for the exoplanet Qatar-1b, 10 new transit light curves are presented and the TTV analysis with a baseline of 1400 epochs are performed. Because the linear model provides a good fitting with reduced chi-square = 2.59 and the false-alarm probabilities of possible TTV frequencies are as large as 35 %, our results are consistent with a null-TTV model. Nevertheless, a new ephemeris with the reference time T_0 = 2455647.63360\pm 0.00008 (BJD) and the period P= 1.4200236\pm 0.0000001 (day) is obtained. In…
We report the discovery of Qatar-6b, a new transiting planet identified by the Qatar Exoplanet Survey (QES). The planet orbits a relatively bright (V=11.44), early-K main-sequence star at an orbital period of P~3.506 days. An SED fit to available multi-band photometry, ranging from the near-UV to the mid-IR, yields a distance of d = 101 +/- 6 pc to the system. From a global fit to follow-up photometric and spectroscopic observations, we calculate the mass and radius of the planet to be Mp = 0.67 +/- 0.07 Mjup and Rp = 1.06 +/- 0.07 Rjup, respectively. We use multi-color photometric light curve…
We present an analysis of the Qatar-1 and TrES-5 transiting exoplanetary systems, which contain Jupiter-like planets on short-period orbits around K-dwarf stars. Our data comprise a total of 20 transit light curves obtained using five medium-class telescopes, operated using the defocussing technique. The average precision we reach in all our data is $RMS_{Q} = 1.1$ mmag for Qatar-1 ($V = 12.8$) and $RMS_{T} = 1.0$ mmag for TrES-5 ($V = 13.7$). We use these data to refine the orbital ephemeris, photometric parameters, and measured physical properties of the two systems. One transit event for ea…
Till date, only a handful exo-atmospheres have been well characterized, mostly by means of the transit method. Data show exoplanet atmospheres to be diverse. However, this is based on a small number of cases. Here we focus our study on the exo-atmosphere of Qatar-1b, an exoplanet that looks much like HD 189733b regarding its host star activity level, their surface gravity, scale height, equilibrium temperature and transit parameters. Thus, our motivation relied on carrying out a comparative study of their atmospheres, and assess if these are regulated by their environment. In this work we pres…
We announce the detection of recurring sets of recurring starspot occultation events in the short-cadence K2 lightcurve of Qatar-2, a K dwarf star transited every 1.34 d by a hot Jupiter. In total we detect 34 individual starspot occultation events, caused by five different starspots, occulted in up to five consecutive transits or after a full stellar rotation. The longest recurring set of recurring starspot occultations spans over three stellar rotations, setting a lower limit for the longest starspot lifetime of 58 d. Starspot analysis provided a robust stellar rotational period measurement …
We report the discovery and initial characterisation of Qatar-1b, a hot Jupiter orbiting a metal-rich K dwarf star, the first planet discovered by the Alsubai Project exoplanet transit survey. We describe the strategy used to select candidate transiting planets from photometry generated by the Alsubai Project instrument. We examine the rate of astrophysical and other false positives found during the spectroscopic reconnaissance of the initial batch of candidates. A simultaneous fit to the follow-up radial velocities and photometry of Qatar-1b yield a planetary mass of 1.09+/-0.08 Mjup and a ra…
Origins of giant planets on tight orbits, so called hot Jupiters, are a long-lasting question in the planetary formation and evolution theory. The answer seems to be hidden in architectures of those systems that remain only partially understood. Using multi-sector time-series photometry from the Transiting Exoplanet Survey Satellite, we searched for additional planets in the KELT-18, KELT-23, KELT-24, Qatar-8, WASP-62, WASP-100, WASP-119, and WASP-126 planetary systems using both the transit technique and transit timing method. Our homogenous analysis has eliminated the presence of transiting …
We present seventeen high-precision light curves of five transits of the planet Qatar-2b, obtained from four defocussed 2m-class telescopes. Three of the transits were observed simultaneously in the SDSS griz passbands using the seven-beam GROND imager on the MPG/ESO 2.2-m telescope. A fourth was observed simultaneously in Gunn grz using the CAHA 2.2-m telescope with BUSCA, and in r using the Cassini 1.52-m telescope. Every light curve shows small anomalies due to the passage of the planetary shadow over a cool spot on the surface of the host star. We fit the light curves with the prism+gemc m…
The Qatar Exoplanet Survey (QES) is discovering hot Jupiters and aims to discover hot Saturns and hot Neptunes that transit in front of relatively bright host stars. QES currently operates a robotic wide-angle camera system to identify promising transiting exoplanet candidates among which are the confirmed exoplanets Qatar 1b and 2b. This paper describes the first generation QES instrument, observing strategy, data reduction techniques, and follow-up procedures. The QES cameras in New Mexico complement the SuperWASP cameras in the Canary Islands and South Africa, and we have developed tools to…
Ephemeris Refinement for Qatar-4 b, HAT-P-18 b, and CoRoT-1 b with Small Telescope and TESS Observations
Arizona State University（亚利桑那州立大学）；NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory (Code 667)（NASA戈达德太空飞行中心系外行星与恒星天体物理学实验室）
The ability for citizen scientists to analyze image data and search for exoplanets using images from small telescopes has the potential to greatly accelerate the search for exoplanets. Recent work on the Exoplanet Transit Interpretation Code (EXOTIC) enables the generation of high-quality light curves of exoplanet transits given such image data. However, on large image datasets, the photometric analysis of the data and fitting light curves can be a time-consuming process. In this work, we first optimize portions of the EXOTIC codebase to enable faster image processing and curve fitting. Specif…
In the framework of the GAPS project, we are conducting an observational programme aimed at the determination of the orbital obliquity of known transiting exoplanets. The targets are selected to probe the obliquity against a wide range of stellar and planetary physical parameters. We exploit high-precision radial velocity (RV) measurements, delivered by the HARPS-N spectrograph at the 3.6m Telescopio Nazionale Galileo, to measure the Rossiter-McLaughlin (RM) effect in RV time-series bracketing planet transits, and to refine the orbital parameters determinations with out-of-transit RV data. We …
The Qatar-2 transiting exoplanet system was recently observed by the {\it Kepler} telescope as part of {\it K2} Campaign 6. The photometric time series has one-minute time sampling and a precision of about 690~ppm, after filtering out artifacts and spurious trends. We identify dozens of starspot-crossing events, when the planet eclipsed a relatively dark region of the stellar photosphere. The observed patterns in the sequence of these events demonstrate that the planet always transits over the same range of stellar latitudes, and therefore that the stellar obliquity is less than about 10$^\cir…
Previous secondary eclipse observations of the hot Jupiter Qatar-1b in the Ks band suggest that it may have an unusually high day side temperature, indicative of minimal heat redistribution. There have also been indications that the orbit may be slightly eccentric, possibly forced by another planet in the system. We investigate the day side temperature and orbital eccentricity using secondary eclipse observations with Spitzer. We observed the secondary eclipse with Spitzer/IRAC in subarray mode, in both 3.6 and 4.5 micron wavelengths. We used pixel-level decorrelation to correct for Spitzer's …
Uninterrupted observations from space-borne telescopes provide the photometric precision that is required to detect shallow transits of small planets missed by ground-based surveys. We used data from the Transiting Exoplanet Survey Satellite (TESS) to search for nearby planetary companions in 12 planetary systems with hot Jupiters: HD 2685, Qatar-10, WASP-4, WASP-48, WASP-58, WASP-91, WASP-120, WASP-121, WASP-122, WASP-140, XO-6, and XO-7. We also applied the transit timing method based on homogeneously determined mid-transit times in order to search for non-transiting companions that could gr…
We introduce a new transit search and vetting pipeline for observations from the K2 mission, and present the candidate transiting planets identified by this pipeline out of the targets in Campaigns 5 and 6. Our pipeline uses the Gaussian Process-based K2SC code to correct for the K2 pointing systematics and simultaneously model stellar variability. The systematics-corrected, variability-detrended light curves are searched for transits with the Box Least Squares method, and a period-dependent detection threshold is used to generate a preliminary candidate list. Two or three individuals vet each…
Images of the exoplanets TOI 717.01, Qatar-8 b, and HAT-P-3 b were requested in the w-filter from the Las Cumbres Observatory 0.4-meter telescopes. Of these requests, images were taken of TOI 717.01 and HAT-P-3b and were reduced using the EXOplanet Transit Interpretation Code (EXOTIC) software, as well as 6 photometric algorithms from the Our Solar Siblings pipeline. The transit midpoint for HAT-P-3 b was found to be 2458907.6205, which is 20.2 minutes different from its expected midpoint that night. For TOI 717.01, the transit was not discernible, likely due to its low transit depth of 0.1%. …
The transit timing variation technique (TTV) has been widely used to detect and characterize multiple planetary systems. Due to the observational biases imposed mainly by the photometric conditions and instrumentation and the high signal-to-noise required to produce primary transit observations, ground-based data acquired using small telescopes limit the technique to the follow-up of hot Jupiters. However, space-based missions such as Kepler and CoRoT have already revealed that hot Jupiters are mainly found in single systems. Thus, it is natural to question ourselves if we are properly using t…
Five newly observed transit light curves of the TrES-3 planetary system are presented. Together with other light curve data from literature, 23 transit light curves in total, which cover an overall timescale of 911 epochs, have been analyzed through a standard procedure. From these observational data, the system's orbital parameters are determined and possible transit timing variations are investigated. Given that a null transit-timing-variation produces a fit with reduced chi^2=1.52, our results agree with previous work, that transit timing variations might not exist in these data. However, a…
We present 6 new transits of the system WASP-4. Together with 28 light curves published in the literature, we perform an homogeneous study of its parameters and search for variations in the transit's central times. The final values agree with those previously reported, except for a slightly lower inclination. We find no significant long-term variations in $i$ or $R_{P}/R_{\star}$. The $O-C$ mid-transit times do not show signs of TTVs greater than 54 s.
The Kepler Space Telescope has discovered thousands of planets via the transit method. The transit timing variations of these planets allows us not only to infer the existence of other planets, transiting or not, but to characterize a number of parameters of the system. Using the transit timing variations of the planets Kepler-159b and 159c, the transit simulator TTVFast, and the Bayesian Inference tool MultiNest, we predict a new non-transiting planet, Kepler-159d, in a resonant 2:1 orbit with Kepler-159c. This configuration is dynamically stable on at least 10 Myr time scales, though we note…
Photometric follow-ups of transiting exoplanets may lead to discoveries of additional, less massive bodies in extrasolar systems. This is possible by detecting and then analysing variations in transit timing of transiting exoplanets. We present photometric observations gathered in 2009 and 2010 for exoplanet WASP-3b during the dedicated transit-timing-variation campaign. The observed transit timing cannot be explained by a constant period but by a periodic variation in the observations minus calculations diagram. Simplified models assuming the existence of a perturbing planet in the system and…
We report nine new transit epochs of the extrasolar planet, observed in the Bessell-I band with SOAR at the Cerro Pachon Observatory and with the SMARTS 1-m Telescope at CTIO, between August 2008 and October 2009. The new transits have been combined with all previously published transit data for this planet to provide a new Transit Timing Variations (TTVs) analysis of its orbit. We find no evidence of TTVs RMS variations larger than 1 min over a 3 year time span. This result discards the presence of planets more massive than about 5 M_earth, 1 M_earth and 2 M_earth around the 1:2, 5:3 and 2:1 …
Photometric follow-ups of transiting exoplanets (TEPs) may lead to discoveries of additional, less massive bodies in extrasolar systems. This is possible by detecting and then analysing variations in transit timing of transiting exoplanets. In 2009 we launched an international observing campaign, the aim of which is to detect and characterise signals of transit timing variation (TTV) in selected TEPs. The programme is realised by collecting data from 0.6--2.2-m telescopes spread worldwide at different longitudes. We present our observing strategy and summarise first results for WASP-3b with ev…
In this Letter we present observations of recent HAT-P-13b transits. The combined analysis of published and newly obtained transit epochs shows evidence for significant transit timing variations since the last publicly available ephemerides. Variation of transit timings result in a sudden switch of transit times. The detected full range of TTV spans ~0.015 days, which is significantly more than the known TTV events exhibited by hot Jupiters. If we have detected a periodic process, its period should be at least ~3 years because there are no signs of variations in the previous observations. This…
Here we describe a story behind the discovery of Kepler-46, which was the first exoplanetary system detected and characterized from a method known as the transit timing variations (TTVs). The TTV method relies on the gravitational interaction between planets orbiting the same star. If transits of at least one of the planets are detected, precise measurements of its transit times can be used, at least in principle, to detect and characterize other non-transiting planets in the system. Kepler-46 was the first case for which this method was shown to work in practice. Other detections and characte…
We develop an analytic model for transit timing variations produced by orbital conjunctions between gravitationally interacting planets. If the planetary orbits have tight orbital spacing, which is a common case among the Kepler planets, the effect of a single conjunction can be best described as: (1) a step-like change of the transit timing ephemeris with subsequent transits of the inner planet being delayed and those of the outer planet being sped up, and (2) a discrete change in sampling of the underlying oscillations from eccentricity-related interaction terms. In the limit of small orbita…
The Transit Timing Variations (TTVs) can be used as a diagnostic of gravitational interactions between planets in a multi-planet system. Many Kepler Objects of Interest (KOIs) exhibit significant TTVs, but KOI-142.01 stands out among them with an unrivaled, 12-hour TTV amplitude. Here we report a thorough analysis of KOI-142.01's transits. We discover periodic Transit Duration Variations (TDVs) of KOI-142.01 that are nearly in phase with the observed TTVs. We show that KOI-142.01's TTVs and TDVs uniquely detect a non-transiting companion with a mass 0.7 that of Jupiter (KOI-142c). KOI-142.01's…
We report the results of the first transit timing variation (TTV) analysis of the very hot Jupiter OGLE-TR-132b, using ten transits collected over a seven-year period. Our analysis combines three previously published transit light curves with seven new transits, which were observed between February 2008 and May 2009 with the new MagIC-e2V instrument on the Magellan Telescopes in Chile. We provide a revised planetary radius of R_p = 1.23+/-0.07 R_J, which is slightly larger than, but consistent within the errors, of the previously published results. Analysis of the planet-to-star radius ratio, …
We detected the transit of HAT-P-6b at HJD 2454698.3908 +/- 0.0011 and that of WASP-1b at HJD 2454774.3448 +/- 0.0023. The updated orbital periods of the planets are 3.852992 +/- 0.000005 days (HAT-P-6b) and 2.519970 +/- 0.000003 days (WASP-1b). There is no indication of any departures from constant orbital period in these systems.
We develop and apply methods to extract planet masses and eccentricities from observed transit time variations (TTVs). First, we derive simple analytic expressions for the TTV that include the effects of both first- and second-order resonances. Second, we use N-body Markov chain Monte Carlo (MCMC) simulations, as well as the analytic formulae, to measure the masses and eccentricities of ten planets discovered by Kepler that have not previously been analyzed. Most of the ten planets have low densities. Using the analytic expressions to partially circumvent degeneracies, we measure small eccentr…
Based on the light an exoplanet blocks from its host star as it passes in front of it during a transit, the mid-transit time can be determined. Periodic variations in mid-transit times can indicate another planet's gravitational influence. We investigate 83 transits of TrES-1 b as observed from 6-inch telescopes in the MicroObservatory robotic telescope network. The EXOTIC data reduction pipeline is used to process these transits, fit transit models to light curves, and calculate transit midpoints. This paper details the methodology for analyzing transit timing variations (TTVs) and using tran…
We identify targets in the Kepler field that may be characterized by transit timing variations (TTVs) and are detectable by the Transiting Exoplanet Survey Satellite (TESS). Despite the reduced signal-to-noise ratio of TESS transits compared to Kepler, we recover 48 transits from 13 systems in Sectors 14, 15, 26, 40 and 41. We find strong evidence of a nontransiting perturber orbiting Kepler-396 (KOI-2672) and explore two possible cases of a third planet in that system that could explain the measured transit times. We update the ephemerides and mass constraints where possible at KOI-70 (Kepler…
The Transit Timing Variation (TTV) method relies on monitoring changes in timing of transits of known exoplanets. Non-transiting planets in the system can be inferred from TTVs by their gravitational interaction with the transiting planet. The TTV method is sensitive to low-mass planets that cannot be detected by other means. Here we describe a fast algorithm that can be used to determine the mass and orbit of the non-transiting planets from the TTV data. We apply our code, ttvim.f, to a wide variety of planetary systems to test the uniqueness of the TTV inversion problem and its dependence on…
A planet's orbital orientation relative to an observer's line of sight determines the chord length for a transiting planet, i.e., the projected distance a transiting planet travels across the stellar disc. For a given circular orbit, the chord length determines the transit duration. Changes in the orbital inclination, the direction of the ascending node, or both, can alter this chord length and thus result in transit duration variations (TDVs). Variation of the full orbital inclination vector can even lead to de-transiting or newly transiting planets for a system. We use Laplace-Lagrange secul…
We present six new transits of the exoplanet OGLE-TR-111b observed with the Magellan Telescopes in Chile between April 2008 and March 2009. We combine these new transits with five previously published transit epochs for this planet between 2005 and 2006 to extend the analysis of transit timing variations reported for this system. We derive a new planetary radius value of 1.019 +/- 0.026 R_J, which is intermediate to the previously reported radii of 1.067 +/- 0.054 R_J (Winn et al. 2007) and 0.922 +/- 0.057 R_J (Diaz et al. 2008). We also examine the transit timing variation and duration change…
While not detected yet, pairs of exoplanets in the 1:1 mean motion resonance probably exist. Low eccentricity, near-planar orbits, which in the comoving frame follow the horseshoe trajectories, are one of the possible stable configurations. Here we study transit timing variations produced by mutual gravitational interaction of planets in this orbital architecture, with the goal to develop methods that can be used to recognize this case in observational data. In particular, we use a semi-analytic model to derive parametric constraints that should facilitate data analysis. We show that character…
We observed Kepler-421 during the anticipated third transit of the snow-line exoplanet Kepler-421b in order to constrain the existence and extent of transit timing variations (TTVs). Previously, the Kepler Spacecraft only observed two transits of Kepler-421b leaving the planet's transit ephemeris unconstrained. Our visible light, time-series observations from the 4.3-meter Discovery Channel Telescope were designed to capture pre-transit baseline and the partial transit of Kepler-421b barring significant TTVs. We use the light curves to assess the probabilities of various transit models using b…
We present new ways to identify single and multiple moons around extrasolar planets using planetary transit timing variations (TTVs) and transit duration variations (TDVs). For planets with one moon, measurements from successive transits exhibit a hitherto undescribed pattern in the TTV-TDV diagram, originating from the stroboscopic sampling of the planet's orbit around the planet-moon barycenter. This pattern is fully determined and analytically predictable after three consecutive transits. The more measurements become available, the more the TTV-TDV diagram approaches an ellipse. For planets…
Systems of two gravitationally bound exoplanets orbiting a common barycenter outside their physical radii ("binary planets") may result from tidal capture during planet-planet scattering. These objects are expected to form in tight orbits of just a few times their summed radii due to dynamical tides. As a result of their close proximity, their transits overlap heavily, leading to the deceptive illusion of a single planet of larger effective size, an effect compounded in the presence of noisy data and/or long integration times. We show that these illusory single-component transits, dubbed "chim…
We present an efficient analytical method to predict the maximum transit timing variations of a circumbinary exoplanet, given some basic parameters of the host binary. We derive an analytical model giving limits on the potential location of transits for coplanar planets orbiting eclipsing binaries, then test it against numerical N-body simulations of a distribution of binaries and planets. We also show the application of the analytic model to Kepler-16b, -34b and -35b. The resulting method is fast, efficient and is accurate to approximately 1% in predicting limits on possible times of transits…
Transit timing analysis may be an effective method of discovering additional bodies in extrasolar systems which harbour transiting exoplanets. The deviations from the Keplerian motion, caused by mutual gravitational interactions between planets, are expected to generate transit timing variations of transiting exoplanets. In 2009 we collected 9 light curves of 8 transits of the exoplanet WASP-10b. Combining these data with published ones, we found that transit timing cannot be explained by a constant period but by a periodic variation. Simplified three-body models which reproduce the observed v…
Stellar magnetic activity is a source of noise in the study of the transits of extrasolar planets. It induces flux variations which affect significantly the transit depth determination and the derivations of planetary and stellar parameters. Furthermore, the colour dependence of stellar activity may significantly influence the characterization of planetary atmospheres. Here we present a systematic approach to quantify the corresponding stellar flux variations as a function of wavelength bands. We consider a star with spots covering a given fraction of its disc and model the variability in the …
The Transit Timing Variations (TTVs) technique provides a powerful tool to detect additional planets in transiting exoplanetary systems. In this paper we show how transiting planets with significant TTVs can be systematically missed, or cataloged as false positives, by current transit search algorithms, unless they are in multi-transit systems. If the period of the TTVs, P_TTV, is longer than the time baseline of the observations and its amplitude, A_TTV, is larger than the timing precision limit of the data, transiting planet candidates are still detected, but with incorrect ephemerides. Ther…
[ABRIDGED] Since the discovery of the first transiting extrasolar planet, transit timing has been recognized as a powerful method to discover and characterize additional planets in these systems. However, the gravitational influence of additional planets is not the only expected source of transit timing variations. In this work, we derive the expected detection frequency of stellar companions of hot-jupiter transiting planets host-stars, detectable by means of transit timing analysis. Since roughly half of the stars in the solar neighborhood belong to binary or multiple stellar systems, the sa…
Motivated by the previously reported high orbital decay rate of the planet WASP-43b, eight newly transit light curves are obtained and presented. Together with other data in literature, we perform a self-consistent timing analysis with data covering a timescale of 1849 epochs. The results give an orbital decay rate dP/dt = -0.02890795\pm 0.00772547 sec/year, which is one order smaller than previous values. This slow decay rate corresponds to a normally assumed theoretical value of stellar tidal dissipation factor. In addition, through the frequency analysis, the transit timing variations prese…
The hot-Jupiter WASP-10b was reported by Maciejewski et al. (2011a,b) to show transit timing variations (TTV) with an amplitude of ~ 3.5 minutes. These authors proposed that the observed TTVs were caused by a 0.1 MJup perturbing companion with an orbital period of ~ 5.23 d, and hence, close to the outer 5:3 mean motion resonance with WASP-10b. To test this scenario, we present eight new transit light curves of WASP-10b obtained with the Faulkes Telescope North and the Liverpool Telescope. The new light curves, together with 22 previously published ones, were modelled with a Markov-Chain Monte-…
The Kepler Mission is monitoring the brightness of ~150,000 stars searching for evidence of planetary transits. As part of the "Hunt for Exomoons with Kepler" (HEK) project, we report a planetary system with two confirmed planets and one candidate planet discovered using the publicly available data for KOI-872. Planet b transits the host star with a period P_b=33.6d and exhibits large transit timing variations indicative of a perturber. Dynamical modeling uniquely detects an outer nontransiting planet c near the 5:3 resonance (P_c=57.0d) of mass 0.37 times that of Jupiter. Transits of a third …
We report on the detection of transit timing variations (TTV) of WASP-161b by using the combination of TESS data and archival data. The midpoint of the transits in TESS data are offset by $\sim$67 minutes in Jan. 2019, and $\sim$203 minutes in Jan. 2021, based on the ephemeris published in previous work. We are able to reproduce the transit timings from the archival light curve (SSO-Europa; Jan. 2018) and find SSO-Europa timing is consistent with the published ephemeris under a constant period assumption. Conversely, we find that the SSO-Europa transit midpoint indicates a 6.62-minute variatio…
Considering the importance of investigating the transit timing variations (TTVs) of transiting exoplanets, we present a follow-up study of HAT-P-12b. We include six new light curves observed between 2011 and 2015 from three different observatories, in association with 25 light curves taken from the published literature. The sample of the data used, thus covers a time span of about 10.2 years with a large coverage of epochs (1160) for the transiting events of the exoplanet HAT-P-12b. The light curves are used to determine the orbital parameters and conduct an investigation of possible transit t…
The measurement of an exoplanet's oblateness and obliquity provides insights into the planet's internal structure and formation history. Previous work using small differences in the shape of the transit light curve has been moderately successful, but was hampered by the small signal and extreme photometric precision required. The measurement of changes in transit depth, caused by the spin precession of an oblate planet, was proposed as an alternative method. Here, we present the first attempt to measure these changes. Using Kepler photometry, we examined the brown dwarf Kepler-39b and the warm…
