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1.
We report on observations of transit events of the transiting planets XO‐1b and TrES‐1 with a 25 cm telescope of the University Observatory Jena. With the transit timings for XO‐1b from all 50 available XO, SuperWASP, Transit Light Curve (TLC)‐Project‐ and Exoplanet Transit Database (ETD)‐data, including our own I ‐band photometry obtained in March 2007, we find that the orbital period is P = (3.941501 ± 0.000001) d, a slight change by ∼3 s compared to the previously published period. We present new ephemeris for this transiting planet. Furthermore, we present new R ‐band photometry of two transits of TrES‐1. With the help of all available transit times from literature this allows us to refine the estimate of the orbital period: P = (3.0300722 ± 0.0000002) d. Our observations will be useful for future investigations of timing variations caused by additional perturbing planets and/or stellar spots and/or moons (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

2.
Transiting exoplanetary systems are surpassingly important among the planetary systems since they provide the widest spectrum of information for both the planet and the host star. If a transiting planet is on an eccentric orbit, the duration of transits T D is sensitive to the orientation of the orbital ellipse relative to the line of sight. The precession of the orbit results in a systematic variation in both the duration of individual transit events and the observed period between successive transits,   P obs  . The periastron of the ellipse slowly precesses due to general relativity and possibly the presence of other planets in the system. This secular precession can be detected through the long-term change in   P obs  (transit timing variations, TTV) or in T D (transit duration variations, TDV). We estimate the corresponding precession measurement precision for repeated future observations of the known eccentric transiting exoplanetary systems (XO-3b, HD 147506b, GJ 436b and HD 17156b) using existing or planned space-borne instruments. The TDV measurement improves the precession detection sensitivity by orders of magnitude over the TTV measurement. We find that TDV measurements over a approximately 4 yr period can typically detect the precession rate to a precision well exceeding the level predicted by general relativity.  相似文献   

3.
We present results from a search for additional transiting planets in 24 systems already known to contain a transiting planet. We model the transits due to the known planet in each system and subtract these models from light curves obtained with the SuperWASP (Wide Angle Search for Planets) survey instruments. These residual light curves are then searched for evidence of additional periodic transit events. Although we do not find any evidence for additional planets in any of the planetary systems studied, we are able to characterize our ability to find such planets by means of Monte Carlo simulations. Artificially generated transit signals corresponding to planets with a range of sizes and orbital periods were injected into the SuperWASP photometry and the resulting light curves searched for planets. As a result, the detection efficiency as a function of both the radius and orbital period of any second planet is calculated. We determine that there is a good (>50 per cent) chance of detecting additional, Saturn-sized planets in   P ∼  10 d orbits around planet-hosting stars that have several seasons of SuperWASP photometry. Additionally, we confirm previous evidence of the rotational stellar variability of WASP-10, and refine the period of rotation. We find that the period of the rotation is  11.91 ± 0.05  d, and the false alarm probability for this period is extremely low  (∼10−13)  .  相似文献   

4.
We describe a method of estimating the abundance of short-period extra-solar planets based on the results of a photometric survey for planetary transits. We apply the method to a 21-night survey with the 2.5-m Isaac Newton Telescope of ∼32 000 stars in a ∼0.5 × 0.5 deg2 field including the open cluster NGC 7789. From the colour–magnitude diagram, we estimate the mass and radius of each star by comparison with the cluster main sequence. We search for injected synthetic transits throughout the light curve of each star in order to determine their recovery rate, and thus calculate the expected number of transit detections and false alarms in the survey. We take proper account of the photometric accuracy, time sampling of the observations and criteria (signal-to-noise ratio and number of transits) adopted for transit detection. Assuming that none of the transit candidates found in the survey will be confirmed as real planets, we place conservative upper limits on the abundance of planets as a function of planet radius, orbital period and spectral type.  相似文献   

5.
The TrES‐2 system harbors one planet which was discovered with the transit technique. In this work we investigate the dynamical behavior of possible additional, lower‐mass planets. We identify the regions where such planets can move on stable orbits and show how they depend on the initial eccentricity and inclination. We find, that there are stable regions inside and outside the orbit of TrES‐2b where additional, smaller planets can move. We also show that those planets can have a large orbital inclination which makes a detection with the transit technique very difficult (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

6.
A unique short‐period (P = 0.65356(1) d) Mercury‐size Kepler exoplanet candidate KIC012557548b has been discovered recently by Rappaport et al. (2012). This object is a transiting disintegrating exoplanet with a circum‐planetary material–comet‐like tail. Close‐in exoplanets, like KIC012557548b, are subjected to the greatest planet‐star interactions. This interaction may have various forms. In certain cases it may cause formation of the comet‐like tail. Strong interaction with the host star, and/or presence of an additional planet may lead to variations in the orbital period of the planet. Our main aim is to search for comet‐like tails similar to KIC012557548b and for long‐term orbital period variations. We are curious about frequency of comet‐like tail formation among short‐period Kepler exoplanet candidates. We concentrate on a sample of 20 close‐in candidates with a period similar to KIC012557548b from the Kepler mission. We first improved the preliminary orbital periods and obtained the transit light curves. Subsequently we searched for the signatures of a circum‐planetary material in these light curves. For this purpose the final transit light curve of each planet was fitted with a theoretical light curve, and the residuals were examined for abnormalities. We then searched for possible long‐term changes of the orbital periods using the method of phase dispersion minimization. In 8 cases out of 20 we found some interesting peculiarities, but none of the exoplanet candidates showed signs of a comet‐like tail. It seems that the frequency of comet‐like tail formation among short‐period Kepler exoplanet candidates is very low. We searched for comet‐like tails based on the period criterion. Based on our results we can conclude that the short‐period criterion is not enough to cause comet‐like tail formation. This result is in agreement with the theory of the thermal wind and planet evaporation (Perez‐Becker & Chiang 2013). We also found 3 cases of candidates which showed some changes of the orbital period. Based on our results we can see that orbital period changes are not caused by comet‐like tail disintegration processes, but rather by possible massive outer companions. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

7.
Of the known transiting extrasolar planets, a few have been detected through photometric follow-up observations of radial velocity planets. Perhaps the best known of these is the transiting exoplanet HD 209458b. For hot Jupiters (periods less than ∼5 d), the a priori information that 10 per cent of these planets will transit their parent star due to the geometric transit probability leads to an estimate of the expected transit yields from radial velocity surveys. The radial velocity information can be used to construct an effective photometric follow-up strategy which will provide optimal detection of possible transits. Since the planet-harbouring stars are already known in this case, one is only limited by the photometric precision achievable by the chosen telescope/instrument. The radial velocity modelling code presented here automatically produces a transit ephemeris for each planet data set fitted by the program. Since the transit duration is brief compared with the fitted period, we calculate the maximum window for obtaining photometric transit observations after the radial velocity data have been obtained, generalizing for eccentric orbits. We discuss a typically employed survey strategy which may contribute to a possible radial velocity bias against detection of the very hot Jupiters which have dominated the transit discoveries. Finally, we describe how these methods can be applied to current and future radial velocity surveys.  相似文献   

8.
在掩星法发现的系外行星系统中,如果存在其他未知的伴星绕同一颗恒星运动,掩星行星由于受到伴星引力的影响,运动轨道将发生变化,轨道周期不再是常数,而是变化的。利用这种变化探测掩星系统中的其他行星,已成为一种新的方法。主要介绍了未知行星与掩星行星之间的引力作用引起的掩星周期变化效应,以及掩星周期变化法探测系外行星的理论和研究进展状况,最后简要讨论了几种影响掩星周期变化的其他因素:共轨行星、卫星、潮汐效应、相对论效应及恒星的引力四极矩等。  相似文献   

9.
We present the results of an extensive study of the detectability of Earth-sized planets and super-Earths in the habitable zones of cool and low-mass stars using transit timing variation method. We have considered a system consisting of a star, a transiting giant planet, and a terrestrial-class perturber, and calculated TTVs for different values of the parameters of the system. To identify ranges of the parameters for which these variations would be detectable by Kepler, we considered the analysis presented by Ford et?al. (Transit timing observations from Kepler: I. Statistical analysis of the first four months. ArXiv:1102.0544, 2011) and assumed that a peak-to-peak variation of 20 s would be within the range of the photometric sensitivity of this telescope. We carried out simulations for resonant and non-resonant orbits, and identified ranges of the semimajor axes and eccentricities of the transiting and perturbing bodies for which an Earth-sized planet or a super-Earth in the habitable zone of a low-mass star would produce such TTVs. Results of our simulations indicate that in general, outer perturbers near first- and second-order resonances show a higher prospect for detection. Inner perturbers are potentially detectable only when near 1:2 and 1:3 mean-motion resonances. For a typical M star with a Jupiter-mass transiting planet, for instance, an Earth-mass perturber in the habitable zone can produce detectable TTVs when the orbit of the transiting planet is between 15 and 80 days. We present the details of our simulations and discuss the implication of the results for the detection of terrestrial planets around different low-mass stars.  相似文献   

10.
We report the discovery of WASP-10b, a new transiting extrasolar planet (ESP) discovered by the Wide Angle Search for Planets (WASP) Consortium and confirmed using Nordic Optical Telescope FIbre-fed Echelle Spectrograph and SOPHIE radial velocity data. A 3.09-d period, 29 mmag transit depth and 2.36 h duration are derived for WASP-10b using WASP and high-precision photometric observations. Simultaneous fitting to the photometric and radial velocity data using a Markov Chain Monte Carlo procedure leads to a planet radius of  1.28 R J   , a mass of  2.96 M J   and eccentricity of ≈0.06. WASP-10b is one of the more massive transiting ESPs, and we compare its characteristics to the current sample of transiting ESP, where there is currently little information for masses greater than ≈  2 M J   and non-zero eccentricities. WASP-10's host star, GSC 2752−00114 (USNO-B1.0 1214−0586164) is among the fainter stars in the WASP sample, with   V = 12.7  and a spectral type of K5. This result shows promise for future late-type dwarf star surveys.  相似文献   

11.
The Wide Angle Search for Planets (WASP) survey currently operates two installations, designated SuperWASP-N and SuperWASP-S, located in the Northern and Southern hemispheres, respectively. These installations are designed to provide high time-resolution photometry for the purpose of detecting transiting extrasolar planets, asteroids, and transient events. Here, we present results from a transit-hunting observing campaign using SuperWASP-N covering a right ascension (RA) range of 06h < RA < 16h. This paper represents the fifth and final in the series of transit candidates released from the 2004 observing season. In total, 729 335 stars from 33 fields were monitored with 130 566 having sufficient precision to be scanned for transit signatures. Using a robust transit detection algorithm and selection criteria, six stars were found to have events consistent with the signature of a transiting extrasolar planet based on the photometry, including the known transiting planet XO-1b. These transit candidates are presented here along with discussion of follow-up observations and the expected number of candidates in relation to the overall observing strategy.  相似文献   

12.
A young hot Jupiter might have been tidally inflated beyond its Roche radius when its orbit was being circularized. This scenario has the potential to explain a couple of solid or tentative observations such as a pile‐up of hot Jupiters around 0.04‐0.05 AU, the mass‐period correlation of transiting planets, as well as the existence of hot Neptunes. Other scenarios such as tidal dissipation in a planet‐host star as well as the magnetic interaction will be also discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

13.
We present the first follow‐up study of the transiting system WASP‐41 after its discovery in 2011. The main goal of this paper is to refine the physical parameters of the system and search for possible signs of transit timing variations. The observations used for analysis were taken from the public archive of the Exoplanet Transit Database (ETD). Assuming three different limb darkening laws, we found the best‐fitting model and redetermined parameters of the system. Although system parameters obtained in this study were found to be in good agreement with the discovery study, the planetary radius determined here is notably smaller, namely 1.12+0.06 –0.07 RJup. The Safronov number Θ = 0.071 ± 0.002 and equilibrium temperature Teq = 1271 ± 50 K were also determined. Both values indicate that the planet WASP‐41b belongs to Class I of transiting planets. No significant transit timing variations were detected. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

14.
We propose that the presence of additional planets in extrasolar planetary systems can be detected by long-term transit timing studies. If a transiting planet is on an eccentric orbit then the presence of another planet causes a secular advance of the transiting planet's pericentre over and above the effect of general relativity. Although this secular effect is impractical to detect over a small number of orbits, it causes long-term differences when future transits occur, much like the long-term decay observed in pulsars. Measuring this transit-timing delay would thus allow the detection of either one or more additional planets in the system or the first measurements of non-zero oblateness ( J 2) of the central stars.  相似文献   

15.
We report the discovery of a 7.3 M J exoplanet WASP-14b, one of the most massive transiting exoplanets observed to date. The planet orbits the 10th-magnitude F5V star USNO-B1 11118−0262485 with a period of 2.243 752 d and orbital eccentricity   e = 0.09  . A simultaneous fit of the transit light curve and radial velocity measurements yields a planetary mass of 7.3 ± 0.5 M J and a radius of 1.28 ± 0.08 R J. This leads to a mean density of about 4.6 g cm−3 making it the densest transiting exoplanets yet found at an orbital period less than 3 d. We estimate this system to be at a distance of  160 ± 20  pc. Spectral analysis of the host star reveals a temperature of  6475 ± 100 K, log  g = 4.07  cm s−2 and   v sin  i = 4.9 ± 1.0  km s−1, and also a high lithium abundance,  log  N (Li) = 2.84 ± 0.05  . The stellar density, effective temperature and rotation rate suggest an age for the system of about 0.5–1.0 Gyr.  相似文献   

16.
To date, two planetary systems have been discovered with close-in, terrestrial-mass planets     . Many more such discoveries are anticipated in the coming years with radial velocity and transit searches. Here we investigate the different mechanisms that could form 'hot Earths' and their observable predictions. Models include: (1) in situ accretion; (2) formation at larger orbital distance followed by inward 'type 1' migration; (3) formation from material being 'shepherded' inward by a migrating gas giant planet; (4) formation from material being shepherded by moving secular resonances during dispersal of the protoplanetary disc; (5) tidal circularization of eccentric terrestrial planets with close-in perihelion distances and (6) photoevaporative mass-loss of a close-in giant planet. Models 1–4 have been validated in previous work. We show that tidal circularization can form hot Earths, but only for relatively massive planets     with very close-in perihelion distances (≲0.025 au), and even then the net inward movement in orbital distance is at most only 0.1–0.15 au. For planets of less than     , photoevaporation can remove the planet's envelope and leave behind the solid core on a Gyr time-scale, but only for planets inside 0.025–0.05 au. Using two quantities that are observable by current and upcoming missions, we show that these models each produce unique signatures, and can be observationally distinguished. These observables are the planetary system architecture (detectable with radial velocities, transits and transit timing) and the bulk composition of transiting close-in terrestrial planets (measured by transits via the planet's radius).  相似文献   

17.
We have carried out an extensive study of the possibility of the detection of Earth-mass and super-Earth Trojan planets using transit timing variation method with the Kepler space telescope. We have considered a system consisting of a transiting Jovian-type planet in a short period orbit, and determined the induced variations in its transit timing due to an Earth-mass/super-Earth Trojan planet. We mapped a large section of the phase space around the 1:1 mean-motion resonance and identified regions corresponding to several other mean-motion resonances where the orbit of the planet would be stable. We calculated transit timing variations (TTVs) for different values of the mass and orbital elements of the transiting and perturbing bodies as well as the mass of central star, and identified orbital configurations of these objects (ranges of their orbital elements and masses) for which the resulted TTVs would be within the range of the variations of the transit timing of Kepler’s planetary candidates. Results of our study indicate that in general, the amplitudes of the TTVs fall within the detectable range of timing precision obtained from the Kepler’s long-cadence data, and depending on the parameters of the system, their magnitudes may become as large as a few hours. The probability of detection is higher for super-Earth Trojans with slightly eccentric orbits around short-period Jovian-type planets with masses slightly smaller than Jupiter. We present the details of our study and discuss the implications of its results.  相似文献   

18.
The geometric calibration of the Planck satellite using the planetary transits is investigated, together with the reconstruction of any offsets from the nominal layout of the focal plane. The methods presented here may be applied to a single focal plane transit of a planet, to find the values of the geometric-calibration parameters at the epoch of the transit or all the transits over the course of the mission. The pointing requirements are easily met, with the pointing reconstruction being dominated by the errors due to the star tracker.  相似文献   

19.
The Hill stability criterion is applied to analyse the stability of a planet in the binary star system of HD 41004 AB, with the primary and secondary separated by 22 AU, and masses of 0.7 M⊙ and 0.4 M⊙, respectively. The primary hosts one planet in an S‐type orbit, and the secondary hosts a brown dwarf (18.64 MJ) on a relatively close orbit, 0.0177 AU, thereby forming another binary pair within this binary system. This star‐brown dwarf pair (HD 41004 B+Bb) is considered a single body during our numerical calculations, while the dynamics of the planet around the primary, HD 41004 Ab, is studied in different phase‐spaces. HD 41004 Ab is a 2.6 MJ planet orbiting at the distance of 1.7 AU with orbital eccentricity 0.39. For the purpose of this study, the system is reduced to a three‐body problem and is solved numerically as the elliptic restricted three‐body problem (ERTBP). The Hill stability function is used as a chaos indicator to configure and analyse the orbital stability of the planet, HD 41004 Ab. The indicator has been effective in measuring the planet's orbital perturbation due to the secondary star during its periastron passage. The calculated Hill stability time series of the planet for the coplanar case shows the stable and quasi‐periodic orbits for at least ten million years. For the reduced ERTBP the stability of the system is also studied for different values of planet's orbital inclination with the binary plane. Also, by recording the planet's ejection time from the system or collision time with a star during the integration period, stability of the system is analysed in a bigger phase‐space of the planet's orbital inclination, ≤ 90°, and its semimajor axis, 1.65–1.75 AU. Based on our analysis it is found that the system can maintain a stable configuration for the planet's orbital inclination as high as 65° relative to the binary plane. The results from the Hill stability criterion and the planet's dynamical lifetime map are found to be consistent with each other. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

20.
We present four new light curves of the 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 unnoticed high level of stellar activity. The rotational period of HAT‐P‐20 A that we obtained from archival data (Prot ≃ 14.5 d), combined with its optical variability and strong emission of Ca ii H & K lines, is consistent with a young stellar age (<1 Gyr) and support the hypothesis that stellar activity may be responsible of the measured deviations of the transit times. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

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