TASTE. III. A homogeneous study of transit time variations in WASP-3b
V. Nascimbeni, A. Cunial, S. Murabito, P. V. Sada, A. Aparicio, G. Piotto, L. R. Bedin, A. P. Milone, A. Rosenberg, L. Borsato, M. Damasso, V. Granata, L. Malavolta
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10 pages, 6 figures, 4 tables; accepted for publication in A&A
The TASTE project is searching for low-mass planets with the Transit Timing Variation (TTV) technique, by gathering high-precision, short-cadence light curves for a selected sample of transiting exoplanets. It has been claimed that the "hot Jupiter" WASP-3b could be perturbed by a second planet. Presenting eleven new light curves (secured at the IAC80 and UDEM telescopes) and re-analyzing thirty-eight archival light curves in a homogeneous way, we show that new data do not confirm the previously claimed TTV signal. However, we bring evidence that measurements are not consistent with a constant orbital period, though no significant periodicity can be detected. Additional dynamical modeling and follow-up observations are planned to constrain the properties of the perturber or to put upper limits to it. We provide a refined ephemeris for WASP-3b and improved orbital/physical parameters. A contact eclipsing binary, serendipitously discovered among field stars, is reported here for the first time.
We present four new light curves of transiting exoplanets WASP-1b and HAT-P-20b, observed within the TASTE (The Asiago Search for Transit timing variations of Exoplanets) project. We re-analyzed light curves from the literature in a homogeneous way, calculating a refined ephemeris and orbital-physical parameters for both objects. WASP-1b does not show any significant Transit Timing Variation signal at the 120 s-level. As for HAT-P-20b, we detected a deviation from our re-estimated linear ephemeris that could be ascribed to the presence of a perturber or, more probably, to a previously unnotice…
We studied three exoplanetary systems with transiting planets: WASP-92, WASP-93 and WASP-118. Using ground-based photometric observations of WASP-92 and WASP-93 and Kepler-K2 observations of WASP-118, we redetermined the orbital and physical parameters of these planets. The precise times of all transits were determined. We constructed O-C diagrams of transits and analysed possible transit timing variations. We did not observe any significant deviation from a linear ephemeris for any of the selected exoplanets. We put upper-mass limits for other hypothetical planets in these systems. Using long…
We recover transits of WASP-18 b and WASP-33 b from Hipparcos (1989-1993) photometry. Marginal detections of HAT-P-56 b and HAT-P-2 b may be also present in the data. New ephemerides are fitted to WASP-18 b and WASP-33 b. A tentative (~1.3 sigma) orbital decay is measured for WASP-18 b, but the implied tidal quality factor (Q' ~ 5 x 10^5) is small and survival time (<10^6 years) is too short to be likely. No orbital decay is measured for WASP-33 b, and a limit of Q' > 2 x 10^5 is placed. For both planets, the uncertainties in published ephemerides appear underestimated: the uncertainty in the …
TASTE (The Asiago Search for Transit timing variations of Exoplanets) project is collecting high-precision, short-cadence light curves for a selected sample of transiting exoplanets. It has been claimed that the hot jupiter HAT-P-13b suddenly deviated from a linear ephemeris by $\sim 20$ min, implying that there is a perturber in the system. Using five new transits, we discuss the plausibility of this transit time variation (TTV), and show that a periodic signal should not be excluded. More follow-up observations are required to constrain the mass and the orbit of the hypothetical perturber.
A promising method to detect earth-sized exoplanets is the timing analysis of a known transit. The technique allows a search for variations in transit duration or center induced by the perturbation of a third body, e.g. a second planet or an exomoon. To this aim, TASTE (The Asiago Survey for Timing transit variations of Exoplanets) project will collect high-precision, short-cadence light curves for a selected sample of transits by using imaging differential photometry at the Asiago 1.82m telescope. The first light curves show that our project can already provide a competitive timing accuracy, …
We present photometric transit observations of the exoplanet WASP-2b using the MTM-500 telescope of the Crimean Astrophysical Observatory of RAS. A brief history of the discovery of the exoplanet WASP-2b and its main characteristics are considered. Observations and the processing procedure are described. The analysis of the obtained results was carried out and compared with information from the ETD and NASA Exoplanet Archive databases. The photometry data of the star WASP-2 and the comparison star GSC 0052201406 are given in the supplementary table.
A promising method for detecting earth-sized exoplanets is the timing analysis of a known transit. The technique allows a search for variations in either the transit duration or the center induced by the perturbation of a third body, e.g. a second planet or an exomoon. By applying this method, the TASTE (The Asiago Search for Transit Timing variations of Exoplanets) project will collect high-precision, short-cadence light curves for a selected sample of transits by using imaging differential photometry at the Asiago 1.82m telescope. The first light curves show that our project can achieve a co…
We report the discovery of two new transiting planets from the WASP survey. WASP-42 b is a 0.500 +/- 0.035 M_jup planet orbiting a K1 star at a separation of 0.0548 +/- 0.0017 AU with a period of 4.9816872 +/- 7.3 x 10^-6 days. The radius of WASP-42 b is 1.080 +/- 0.057 R_jup while its equilibrium temperature is T_eq = 995 +/- 34 K. We detect some evidence for a small but non-zero eccentricity of e=0.060 +/- 0.013. WASP-49 b is a 0.378 +/- 0.027 M_jup planet around an old G6 star. It has a period of 2.7817387 +/- 5.6 x 10^-6 days and a separation of 0.0379 +/- 0.0011 AU. This planet is slightl…
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…
We present seven new transiting hot Jupiters from the WASP-South survey. The planets are all typical hot Jupiters orbiting stars from F4 to K0 with magnitudes of V = 10.3 to 12.5. The orbital periods are all in the range 3.9--4.6 d, the planetary masses range from 0.4--2.3 Mjup and the radii from 1.1--1.4 Mjup. In line with known hot Jupiters, the planetary densities range from Jupiter-like to inflated (rho = 0.13--1.07 rho_jup). We use the increasing numbers of known hot Jupiters to investigate the distribution of their orbital periods and the 3--4-d "pile-up".
We present 22 new transit observations of the exoplanets WASP-18Ab, WASP-19b, and WASP-77Ab, from the Transit Monitoring in the South (TraMoS) project. We simultaneously model our newly collected transit light curves with archival photometry and radial velocity data, to obtain refined physical and orbital parameters. We include TESS light curves of the three exoplanets to perform an extended analysis of the variations in their transit mid-time (TTV) and to refine their planetary orbital ephemeris. We did not find significant $\rm TTV_{RMS}$ variations larger than 47, 65, and 86 seconds for WAS…
We observed a partial transit of the ultra-hot Jupiter WASP-189 b with PEPSI on the LBT. We detect a highly variable transit signal in multiple atomic transitions, including H-alpha, Fe I, and Mg I. The signal is not consistent with a transiting planetary atmosphere. We suggest instead that the in-transit signal is due to an inhomogeneous stellar surface. Our observations demonstrate the lack of a highly extended atmosphere in common optical atomic tracers. Although WASP-189 is very bright, atmospheric characterization of the planet will be difficult due to the small transit depth and apparent…
As part of our ongoing effort to investigate transit timing variations (TTVs) of known exoplanets, we monitored transits of the four exoplanets HAT-P-18b, HAT-P-19b, HAT-P-27b/WASP-40b and WASP-21b. All of them are suspected to show TTVs due to the known properties of their host systems based on the respective discovery papers. During the past three years 46 transit observations were carried out, mostly using telescopes of the Young Exoplanet Transit Initiative. The analyses are used to refine the systems orbital parameters. In all cases we found no hints for significant TTVs, or changes in th…
We report the detection of two new systems containing transiting planets. Both were identified by WASP as worthy transiting planet candidates. Radial-velocity observations quickly verified that the photometric signals were indeed produced by two transiting hot Jupiters. Our observations also show the presence of additional Doppler signals. In addition to short-period hot Jupiters, we find that the WASP-53 and WASP-81 systems also host brown dwarfs, on fairly eccentric orbits with semi-major axes of a few astronomical units. WASP-53c is over 16 $M_{\rm Jup} \sin i_{\rm c}$ and WASP-81c is 57 $M…
We present a systematic phase curve analysis of known transiting systems observed by the Transiting Exoplanet Survey Satellite (TESS) during year one of the primary mission. Using theoretical predictions for the amplitude of the planetary longitudinal atmospheric brightness modulation, stellar ellipsoidal distortion and Doppler boosting, as well as brightness considerations to select targets with likely detectable signals, we applied a uniform data processing and light-curve modeling framework to fit the full-orbit phase curves of 22 transiting systems with planet-mass or brown dwarf companion…
We used photometric data from the WASP (Wide-Angle Search for Planets) survey to explore the possibility of detecting eclipses and transit signals of brown dwarfs, gas giants and terrestrial companions in close orbit around white dwarfs. We performed extensive Monte Carlo simulations and we found that for Gaussian random noise WASP is sensitive to companions as small as the Moon orbiting a $V\sim$12 white dwarf. For fainter stars WASP is sensitive to increasingly larger bodies. Our sensitivity drops in the presence of co-variant noise structure in the data, nevertheless Earth-size bodies remai…
We present new photometric observations of WASP-15 and WASP-16, two transiting extrasolar planetary systems with measured orbital obliquities but without photometric follow-up since their discovery papers. Our new data for WASP-15 comprise observations of one transit simultaneously in four optical passbands using GROND on the MPG/ESO 2.2m telescope, plus coverage of half a transit from DFOSC on the Danish 1.54m telescope, both at ESO La Silla. For WASP-16 we present observations of four complete transits, all from the Danish telescope. We use these new data to refine the measured physical prop…
We present new transit light curves for planets in six extrasolar planetary systems. They were acquired with 0.4-2.2 m telescopes located in west Asia, Europe, and South America. When combined with literature data, they allowed us to redetermine system parameters in a homogeneous way. Our results for individual systems are in agreement with values reported in previous studies. We refined transit ephemerides and reduced uncertainties of orbital periods by a factor between 2 and 7. No sign of any variations in transit times was detected for the planets studied.
We present the discovery of four new transiting hot jupiters, detected mainly from SuperWASP-North and SOPHIE observations. These new planets, WASP-52b, WASP-58b, WASP-59b, and WASP-60b, have orbital periods ranging from 1.7 to 7.9 days, masses between 0.46 and 0.94 M_Jup, and radii between 0.73 and 1.49 R_Jup. Their G1 to K5 dwarf host stars have V magnitudes in the range 11.7-13.0. The depths of the transits are between 0.6 and 2.7%, depending on the target. With their large radii, WASP-52b and 58b are new cases of low-density, inflated planets, whereas WASP-59b is likely to have a large, de…
WASP-128 is a relatively bright (V= 12.37) G0-dwarf, known to host a transiting brown dwarf in a short-period orbit (Hodžić et al. 2018 arXiv:1807.07557 (H18)). Very few such objects are known, which makes WASP-128 a prime target for further observations to better understand giant planet / brown dwarf properties,including formation and migration histories. To facilitate the planning of future observations of WASP-128b, we improve the orbital ephemeris of the system, by using the seven transits of WASP-128 observed by TESS. We note that our orbital period differs significantly from that of H18:…
We report the discovery of three new transiting hot Jupiters by WASP-South together with the TRAPPIST photometer and the Euler/CORALIE spectrograph. WASP-74b orbits a star of V = 9.7, making it one of the brighter systems accessible to Southern telescopes. It is a 0.95 M_Jup planet with a moderately bloated radius of 1.5 R_Jup in a 2-d orbit around a slightly evolved F9 star. WASP-83b is a Saturn-mass planet at 0.3 M_Jup with a radius of 1.0 R_Jup. It is in a 5-d orbit around a fainter (V = 12.9) G8 star. WASP-89b is a 6 M_Jup planet in a 3-d orbit with an eccentricity of e = 0.2. It is thus s…
WASP-12 b, WASP-33 b, WASP-36 b, and WASP-46 b are four transiting planetary systems which we have studied. These systems' light curves were derived from observations made by the Transiting Light Exoplanet Survey Satellite (TESS) and some ground-based telescopes. We used Exofast-v1 to model these light curves and calculate mid-transit times. Also, we plotted TTV diagrams for them using derived mid-transit times and those available within the literature. O-C analysis of these timings enables us to refine the linear ephemeris of four systems. We measured WASP-12's tidal quality factor based on a…
We present 13 high-precision and four additional light curves of four bright southern-hemisphere transiting planetary systems: WASP-22, WASP-41, WASP-42 and WASP-55. In the cases of WASP-42 and WASP-55, these are the first follow-up observations since their discovery papers. We present refined measurements of the physical properties and orbital ephemerides of all four systems. No indications of transit timing variations were seen. All four planets have radii inflated above those expected from theoretical models of gas-giant planets; WASP-55b is the most discrepant with a mass of 0.63 Mjup and …
We present the fundamental stellar and planetary properties of the transiting planetary system WASP-13 within the framework of the Homogeneous Study of Transiting Systems (HoSTS). HoSTS aims to derive the fundamental stellar (Teff, [Fe/H], Mstar, Rstar), and planetary (Mpl, Rpl, Teq) physical properties of known transiting planets using a consistent methodology and homogeneous high-quality dataset. Four spectral analysis techniques are independently applied to a Keck+HIRES spectrum of WASP-13 considering two distinct cases: unconstrained parameters, and constrained log g from transit light cur…
We describe seven exoplanets transiting stars of brightness V = 10.1 to 12.4. WASP-130b is a "warm Jupiter" having an orbital period of 11.6 d around a metal-rich G6 star. Its mass and radius (1.23 +/- 0.04 Mjup; 0.89 +/- 0.03 Rjup) support the trend that warm Jupiters have smaller radii than hot Jupiters. WASP-131b is a bloated Saturn-mass planet (0.27 Mjup; 1.22 Rjup). Its large scale height and bright (V = 10.1) host star make it a good target for atmospheric characterisation. WASP-132b (0.41 Mjup; 0.87 Rjup) is among the least irradiated and coolest of WASP planets, having a 7.1-d orbit ar…
We have measured the sky-projected spin-orbit alignments for three transiting Hot Jupiters, WASP-103b, WASP-87b, and WASP-66b, using spectroscopic measurements of the Rossiter-McLaughlin effect, with the CYCLOPS2 optical-fiber bundle system feeding the UCLES spectrograph on the Anglo-Australian Telescope. The resulting sky projected spin-orbit angles of $λ= 3^{\circ}\pm33^{\circ}$, $λ= -8^{\circ}\pm11^{\circ}$, and $λ= -4^{\circ}\pm22^{\circ}$ for WASP-103b, WASP-87b, and WASP-66b, respectively, suggest that these three planets are likely on nearly aligned orbits with respect to their host sta…
Near ultraviolet observations of WASP-12b have revealed an early ingress compared to the optical transit lightcurve. This has been interpreted as due to the presence of a magnetospheric bow shock which forms when the relative velocity of the planetary and stellar material is supersonic. We aim to reproduce this observed early ingress by modelling the stellar wind (or coronal plasma) in order to derive the speed and density of the material at the planetary orbital radius. From this we determine the orientation of the shock and the density of compressed plasma behind it. With this model for the …
We present a empirical study of orbital decay for the exoplanet WASP-19b, based on mid-time measurements of 74 complete transits (12 newly obtained by our team and 62 from the literature), covering a 10-year baseline. A linear ephemeris best represents the mid-transit times as a function of epoch. Thus, we detect no evidence of the shortening of WASP-19b's orbital period and establish an upper limit of its steady changing rate, $\dot{P}=-2.294$ ms $yr^{-1}$, and a lower limit for the modified tidal quality factor $Q'_{\star} = (1.23 \pm 0.231) \times 10^{6}$. Both are in agreement with previou…
We present our analysis of the K2 short-cadence data of two previously known hot Jupiter exoplanets: WASP-55b and WASP-75b. The high precision of the K2 lightcurves enabled us to search for transit timing and duration variations, rotational modulation, starspots, phase-curve variations and additional transiting planets. We identified stellar variability in the WASP-75 lightcurve which may be an indication of rotational modulation, with an estimated period of $11.2\pm1.5$ days. We combined this with the spectroscopically measured $v\sin(i_*)$ to calculate a possible line of sight projected incl…
We report the discovery by the WASP transit survey of three new hot Jupiters, WASP-68 b, WASP-73 b and WASP-88 b. WASP-68 b has a mass of 0.95+-0.03 M_Jup, a radius of 1.24-0.06+0.10 R_Jup, and orbits a V=10.7 G0-type star (1.24+-0.03 M_sun, 1.69-0.06+0.11 R_sun, T_eff=5911+-60 K) with a period of 5.084298+-0.000015 days. Its size is typical of hot Jupiters with similar masses. WASP-73 b is significantly more massive (1.88-0.06+0.07 M_Jup) and slightly larger (1.16-0.08+0.12 R_Jup) than Jupiter. It orbits a V=10.5 F9-type star (1.34-0.04+0.05 M_sun, 2.07-0.08+0.19 R_sun, T_eff=6036+-120 K) eve…
We report the discovery of the transiting exoplanets WASP-69b, WASP-70Ab and WASP-84b, each of which orbits a bright star ($V\sim10)$. WASP-69b is a bloated Saturn-mass planet (0.26 $M_{\rm Jup}$, 1.06 $R_{\rm Jup}$) in a 3.868-d period around an active, $\sim$1-Gyr, mid-K dwarf. ROSAT detected X-rays $60 \pm 27"$ from WASP-69. If the star is the source then the planet could be undergoing mass-loss at a rate of $\sim$10$^{12}$ g s$^{-1}$. This is 1 to 2 orders of magnitude higher than the evaporation rate estimated for HD 209458b and HD 189733b, both of which have exhibited anomalously-large L…
High-precision transit observations provide excellent opportunities for characterizing the physical properties of exoplanetary systems. These physical properties supply many pieces of information for unvealing the internal structure, external atmosphere, and dynamical history of the planets. We present revised properties of transiting systems WASP-35 and HAT-P-30/WASP-51 through analyzing newly available TESS photometry and ground-based observations obtained at 1m telescope of Yunnan Observatories as well as from the literature. The improved system parameters are consistent with the previous r…
WASP-103b is the exoplanet with the highest expected deformation signature in its transit light curve and one of the shortest expected spiral-in times. Measuring the tidal deformation of the planet would allow us to estimate the second degree fluid Love number and gain insight into the planet's internal structure. Moreover, measuring the tidal decay timescale would allow us to estimate the stellar tidal quality factor, which is key to constraining stellar physics. We obtained 12 transit light curves of WASP-103b with the CHEOPS to estimate the tidal deformation and tidal decay of this extreme …
We report on four new transiting hot Jupiters discovered by the WASP-South survey. WASP-178b transits a V = 9.9, A1V star with Teff = 9350 +/- 150 K, the second-hottest transit host known. It has a highly bloated radius of 1.81 +/- 0.09 Rjup, in line with the known correlation between high irradiation and large size. With an estimated temperature of 2470 +/- 60 K, the planet is one of the best targets for studying ultra-hot Jupiters that is visible from the Southern hemisphere. The three host stars WASP-184, WASP-185 and WASP-192 are all post-main-sequence G0 stars of ages 4-8 Gyr. The larger …
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 …
Orbit Refinement of WASP-18 b and Evidence Against the Existence of WASP-18 c
Christ University（基督大学）；Exoplanet Watch（系外行星观测计划）；California State University, San Marcos（圣马科斯加州州立大学）；University of California, Riverside（加州大学河滨分校）；Mackenzie Presbyterian University（麦肯锡长老会大学）；American Association of Variable Star Observers（变星观测者美国协会）
利用 205 条凌星光变曲线和 449 条径向速度测量，精化 WASP-18 b 的轨道历元并检验 WASP-18 c 的存在性，发现凌星计时和径向速度数据均不支持 WASP-18 c 的存在。
We have used photometry from the WASP-South instrument to identify 5 stars showing planet-like transits in their light curves. The planetary nature of the companions to these stars has been confirmed using photometry from the EulerCam instrument on the Swiss Euler 1.2-m telescope and the TRAPPIST telescope, and spectroscopy obtained with the CORALIE spectrograph. The planets discovered are hot Jupiter systems with orbital periods in the range 2.17 to 5.75 days, masses from 0.3M$_{\rm Jup}$ to 1.2M$_{\rm Jup}$ and with radii from 1R$_{\rm Jup}$ to 1.5R$_{\rm Jup}$. These planets orbit bright st…
By analysing the short-cadence K2 photometry from the observing Campaign 12 we refine the system parameters of hot Jupiter WASP-28b and hot Saturn WASP-151b. We report the non-detection and corresponding upper limits for transit-timing and transit-duration variations, starspots, rotational and phase-curve modulations and additional transiting planets. We discuss the cause of several background brightening events detected simultaneously in both planetary systems and conclude that they are likely associated with the passage of Mars across the field of view.
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 present precise radial-velocity measurements of WASP-1 and WASP-2 throughout transits of their giant planets. Our goal was to detect the Rossiter-McLaughlin (RM) effect, the anomalous radial velocity observed during eclipses of rotating stars, which can be used to study the obliquities of planet-hosting stars. For WASP-1 a weak signal of a prograde orbit was detected with ~2sigma confidence, and for WASP-2 no signal was detected. The resulting upper bounds on the RM amplitude have different implications for these two systems, because of the contrasting transit geometries and the stellar typ…
Stellar activity is one of the main obstacles to high-precision exoplanet observations and has motivated extensive studies in detection and characterization problems. Most efforts focused on unocculted starspots in optical transit spectrophotometry, while the impact of starspot crossings is assumed to be negligible in the near-infrared. Here, we present \textit{HST}/WFC3 transit observations of the active star WASP-52, hosting an inflated hot Jupiter, which present a possible starspot occultation signal. By using this data set as a benchmark, we investigated whether the masking of the transit …
We report analysis of transit spectroscopy of the extrasolar planets WASP-12 b, WASP-17 b, and WASP-19 b using the Wide Field Camera 3 on the HST. We analyze the data for a single transit for each planet using a strategy similar in certain aspects to the techniques used by Berta et al. (2012), but we extend their methodology to allow us to correct for channel- or wavelength-dependent instrumental effects by utilizing the band-integrated time series and measurements of the drift of the spectrum on the detector over time. We achieve almost photon-limited results for individual spectral bins, but…
We have performed extensive simulations to explore the possibility of detecting eclipses and transits of close, sub-stellar and planetary companions to white dwarfs in WASP light-curves. Our simulations cover companions $\sim0.3\Re<{\rm R}_{pl}<12\Re$ and orbital periods $2{\rm h}<P<15{\rm d}$, equivalent to orbital radii $0.003{\rm AU} < a < 0.1{\rm AU}$. For Gaussian random noise WASP is sensitive to transits by companions as small as the Moon orbiting a $\textrm{V}\simeq$12 white dwarf. For fainter white dwarfs WASP is sensitive to increasingly larger radius bodies. However, in the presence…
Although WASP-14 b is one of the most massive and densest exoplanets on a tight and eccentric orbit, it has never been a target of photometric follow-up monitoring or dedicated observing campaigns. We report on new photometric transit observations of WASP-14 b obtained within the framework of "Transit Timing Variations @ Young Exoplanet Transit Initiative" (TTV@YETI). We collected 19 light-curves of 13 individual transit events using six telescopes located in five observatories distributed in Europe and Asia. From light curve modelling, we determined the planetary, stellar, and geometrical pro…
We measured the chromospheric activity of the four hot Jupiter hosts WASP-43, WASP-51/HAT-P-30, WASP-72 & WASP-103 to search for anomalous values caused by the close-in companions. The Mount Wilson Ca II H&K S-index was calculated for each star using observations taken with the Robert Stobie Spectrograph at the Southern African Large Telescope. The activity level of WASP-43 is anomalously high relative to its age and falls among the highest values of all known main sequence stars. We found marginal evidence that the activity of WASP-103 is also higher than expected from the system age. We sugg…
We present observations of the Rossiter-McLaughlin effect for the transiting exoplanet systems WASP-1, WASP-24, WASP-38 and HAT-P-8, and deduce the orientations of the planetary orbits with respect to the host stars' rotation axes. The planets WASP-24b, WASP-38b and HAT-P-8b appear to move in prograde orbits and be well aligned, having sky-projected spin orbit angles consistent with zero: λ = -4.7 \pm 4.0°, λ = 15 + 33°/-43° and λ = -9.7 +9.0°/-7.7°, respectively. The host stars have Teff < 6250 K and conform with the trend of cooler stars having low obliquities. WASP-38b is a massive planet o…
We report the discovery from the WASP survey of two exoplanetary systems, each consisting of a Jupiter-sized planet transiting an 11th magnitude (V) main-sequence star. WASP-104b orbits its star in 1.75 d, whereas WASP-106b has the fourth-longest orbital period of any planet discovered by means of transits observed from the ground, orbiting every 9.29 d. Each planet is more massive than Jupiter (WASP-104b has a mass of $1.27 \pm 0.05 \mathrm{M_{Jup}}$, while WASP-106b has a mass of $1.93 \pm 0.08 \mathrm{M_{Jup}}$). Both planets are just slightly larger than Jupiter, with radii of $1.14 \pm 0.…
We have developed a new model for analysing light curves of planetary transits when there are starspots on the stellar disc. Because the parameter space contains a profusion of local minima we developed a new optimisation algorithm which combines the global minimisation power of a genetic algorithm and the Bayesian statistical analysis of the Markov chain. With these tools we modelled three transit light curves of WASP-19. Two light curves were obtained on consecutive nights and contain anomalies which we confirm as being due to the same spot. Using these data we measure the star's rotation pe…
We report twelve new transit observations of the exoplanet WASP-4b from the Transit Monitoring in the South Project (TraMoS) project. These transits are combined with all previously published transit data for this planet to provide an improved radius measurement of Rp = 1.395 +- 0.022 Rjup and improved transit ephemerides. In a new homogeneous analysis in search for Transit Timing Variations (TTVs) we find no evidence of those with RMS amplitudes larger than 20 seconds over a 4-year time span. This lack of TTVs rules out the presence of additional planets in the system with masses larger than …
Theoretical calculations and some indirect observations show that massive exoplanets on tight orbits must decay due to tidal dissipation within their host stars. This orbital evolution could be observationally accessible through precise transit timing over a course of decades. The rate of planetary in-spiralling may not only help us to understand some aspects of evolution of planetary systems, but also can be used as a probe of the stellar internal structure. In this paper we present results of transit timing campaigns organised for a carefully selected sample of hot Jupiter-like planets which…
We present here observations of the transit of WASP-10b on 14 October 2009 UT taken from the University of Arizona's 1.55 meter Kuiper telescope on Mt. Bigelow. Conditions were photometric and accuracies of 2.0 mmag RMS were obtained throughout the transit. We have found that the ratio of the planet to host star radii is in agreement with the measurements of Christian et al. (2008) instead of the refinements of Johnson et al. (2009), suggesting that WASP-10b is indeed inflated beyond what is expected from theoretical modeling. We find no evidence for large (> 20 s) transit timing variations in…
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…
The presence of stellar companions around planet hosting stars influences the architecture of their planetary systems. To find and characterise these companions and determine their orbits is thus an important consideration to understand planet formation and evolution. For transiting systems even unbound field stars are of interest if they are within the photometric aperture of the light curve measurement. Then they contribute a constant flux offset to the transit light curve and bias the derivation of the stellar and planetary parameters if their existence is unknown. Close stellar sources are…
We report the discovery of photometric oscillations in the host star of the exoplanet WASP-33 b (HD 15082). The data were obtained in the R band in both transit and out-of-transit phases from the 0.3-m telescope and the Montcabrer Observatory and the 0.8-m telescope at the Montsec Astronomical Observatory. Proper fitting and subsequent removal of the transit signal reveals stellar photometric variations with a semi-amplitude of about 1 mmag. The detailed analysis of the periodogram yields a structure of significant signals around a frequency of 21 cyc per day, which is typical of delta Scuti-t…
A transiting planetary system was discovered independently by two groups, under the names WASP-86 (Faedi et al. 2016) and KELT-12 (Stevens et al. 2017). The properties of the system determined in these works were very different, most tellingly a variation of a factor of three in the measured radius of the planet. We suggest that the system be named WASP-86/KELT-12 to better apportion the credit for discovery between the two groups. We analyse the light curve of this system from the Transiting Exoplanet Survey Satellite, which observed it in two sectors, following the Homogeneous Studies approa…
We present the discovery of WASP-39b, a highly inflated transiting Saturn-mass planet orbiting a late G-type dwarf star with a period of $4.055259 \pm 0.000008$\,d, Transit Epoch T$_{0}=2455342.9688\pm0.0002$\,(HJD), of duration $0.1168 \pm 0.0008$\,d. A combined analysis of the WASP photometry, high-precision follow-up transit photometry, and radial velocities yield a planetary mass of $\mpl=0.28\pm0.03\,\mj$ and a radius of $\rpl=1.27\pm0.04\,\rj$, resulting in a mean density of $0.14 \pm 0.02\,\rhoj$. The stellar parameters are mass $\mstar = 0.93 \pm 0.03\,\msun$, radius $\rstar = 0.895\pm…
In order to explain the inflated radii of some transiting extrasolar giant planets, we investigate a tidal heating scenario for the inflated planets WASP-4b, WASP-6b, WASP-12b, WASP-15b, and TrES-4. To do so, we assume that they retain a nonzero eccentricity, possibly by dint of continuing interaction with a third body. We calculate the amount of extra heating in the envelope that is then required to fit the radius of each planet, and we explore how this additional power depends on the planetary atmospheric opacity and on the mass of a heavy-element central core. There is a degeneracy between …
An asymmetry between the ingress and egress times was observed in the near-UV light curve of the transit planet WASP-12b. Such asymmetry led us to suggest that the early ingress in the UV light curve of WASP-12b, compared to the optical observations, is caused by a shock around the planet, and that shocks should be a common feature in transiting systems. Here, we classify all the transiting systems known to date according to their potential for producing shocks that could cause observable light curve asymmetries. We found that 36/92 of known transiting systems would lie above a reasonable dete…
