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1.
Transit light curve of KIC012557548b which is best represented by an exoplanet with a comet‐like tail (see Z. Garai et al., this issue, p. 1018). (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

2.
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   

3.
Exoplanet observations have been performed on the automated Pulkovo Observatory telescopes. We have obtained 33 transit light curves for 16 known exoplanets and six transit observations for three exoplanet candidates discovered by the Kepler telescope. Based on our observations, we have reliably confirmed the existence of an exoplanet with an extremely large radius, R pl = 1.83 ± 0.16R Jup, in the system KOI 256 and detected a strong deviation of its orbital revolution from the theoretically predicted one. During the transit of the exoplanet WASP-12b across the stellar disk, we detected bursts that could be caused by the planet transit across spots on the star or by the presence of a satellite around this exoplanet. We detected possible periodic variations in the duration of the exoplanet transit across the stellar disk with time for HAT-P-12b that could be caused by variations in orbital inclination. The transit duration and depth, the central transit time, and the radius and orbital inclination of the planet have been estimated. The equilibrium temperature and albedo have been estimated for several exoplanets.  相似文献   

4.
Paradoxical properties of the KIC 8462852 object discovered in the course the Kepler mission are considered. It has been shown that the assumptions about the nature of the object as a swarm of cometary bodies, fragments resulting from catastrophic collisions of asteroids, or the KIC 8462852b exoplanet meet serious problems and even contradict the Kepler laws, if the eclipsing object is considered as a physical body orbiting a central star. According the energy and other requirements, the hypothetical orbit of KIC 8462852b does not meet the Dyson sphere conception either. In the paper, we used the materials of the study by Boyajian et al. (2015) and the subsequent publications on this theme.  相似文献   

5.
Oort cloud comets occasionally obtain orbits which take them through the planetary region. The perturbations by the planets are likely to change the orbit of the comet. We model this process by using a Monte Carlo method and cross sections for orbital changes, i.e. changes in energy, inclination and perihelion distance, in a single planet-comet encounter. The influence of all major planets is considered. We study the distributions of orbital parameters of observable comets, i.e. those which have perihelion distance smaller than a given value. We find that enough comets are captured from the Oort cloud in order to explain the present populations of short period comets. The median value of cos i for the Jupiter family is 0.985 while it is 0.27 for the Halley types. The results may explain the orbital features of short period comets, assuming that the active lifetime of a comet is not much greater than 400 orbital revolutions.  相似文献   

6.
Previous studies have shown that extrasolar Earth-like planets in close-in habitable zones around M-stars are weakly protected against galactic cosmic rays (GCRs), leading to a strongly increased particle flux to the top of the planetary atmosphere. Two main effects were held responsible for the weak shielding of such an exoplanet: (a) For a close-in planet, the planetary magnetic moment is strongly reduced by tidal locking. Therefore, such a close-in extrasolar planet is not protected by an extended magnetosphere. (b) The small orbital distance of the planet exposes it to a much denser stellar wind than that prevailing at larger orbital distances. This dense stellar wind leads to additional compression of the magnetosphere, which can further reduce the shielding efficiency against GCRs. In this work, we analyse and compare the effect of (a) and (b), showing that the stellar wind variation with orbital distance has little influence on the cosmic ray shielding. Instead, the weak shielding of M star planets can be attributed to their small magnetic moment. We further analyse how the planetary mass and composition influence the planetary magnetic moment, and thus modify the cosmic ray shielding efficiency. We show that more massive planets are not necessarily better protected against galactic cosmic rays, but that the planetary bulk composition can play an important role.  相似文献   

7.
We carried out light‐curve solutions of the ultrashort‐period binaries with MS components observed by Kepler. All six targets turned out almost in thermal contact with contact or slightly overcontact configurations. Two of them, KID 4921906 and KID 6309193, are not eclipsing but reveal ellipsoidal and spot variability. One of the components of KID 8108785 exhibits inherent, quasi‐sinusoidal, small‐amplitude variability. KID 12055255 turned out tobe a very rare case of ultrashort‐period overcontact binary consisting of two M dwarfs. Our modeling indicated that the variability of KID 9532219 is due to eclipses but not to δ Sct pulsations as it was previously supposed. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

8.
Oort cloud comets occasionally obtain orbits which take them through the planetary region. The perturbations by the planets are likely to change the orbit of the comet. We model this process by using a Monte Carlo method and cross sections for orbital changes, i.e. changes in energy, inclination and perihelion distance, in a single planet-comet encounter. The influence of all major planets is considered. We study the distributions of orbital parameters of observable comets, i.e. those which have perihelion distance smaller than a given value. We find that enough comets are captured from the Oort cloud in order to explain the present populations of short period comets. The median value of cos i for the Jupiter family is 0.985 while it is 0.27 for the Halley types. The results may explain the orbital features of short period comets, assuming that the active lifetime of a comet is not much greater than 400 orbital revolutions.  相似文献   

9.
The disciplines of asteroseismology and extrasolar planet science overlap methodically in the branch of high‐precision photometric time series observations. Light curves are, amongst others, useful to measure intrinsic stellar variability due to oscillations, as well as to discover and characterize those extrasolar planets that transit in front of their host stars, periodically causing shallow dips in the observed brightness. Both fields ultimately derive fundamental parameters of stellar and planetary objects, allowing to study for example the physics of various classes of pulsating stars, or the variety of planetary systems, in the overall context of stellar and planetary system formation and evolution. Both methods typically also require extensive spectroscopic follow‐up to fully explore the dynamic characteristics of the processes under investigation. In particularly interesting cases, a combination of observed pulsations and signatures of a planet allows to characterize a system's components to a very high degree of completeness by combining complementary information. The planning of the relevant space missions has consequently converged with respect to science cases, where at the outset there was primarily a coincidence in instrumentation and techniques. Whether space‐ or ground‐based, a specific type of stellar pulsations can themselves be used in an innovative way to search for extrasolar planets. Results from this additional method at the interface of stellar pulsation studies and exoplanet hunts in a beyond‐mainstream area are presented (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

10.
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   

11.
We numerically investigate the dynamics of rotation of several close-in terrestrial exoplanet candidates. In our model, the rotation of the planet is disturbed by the torque of the central star due to the asymmetric equilibrium figure of the planet. We model the shape of the planet by a Jeans spheroid. We use surfaces of section and spectral analysis to explore numerically the rotation phase space of the systems adopting different sets of parameters and initial conditions close to the main spin–orbit resonant states. One of the parameters, the orbital eccentricity, is critically discussed here within the domain of validity of orbital circularization timescales given by tidal models. We show that, depending on some parameters of the system like the radius and mass of the planet, eccentricity etc., the rotation can be strongly perturbed and a chaotic layer around the synchronous state may occupy a significant region of the phase space. 55 Cnc e is an example.  相似文献   

12.
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   

13.
I01 NIR Imaging Spectroscopy of Extrasolar Planets I02 Eccentricity growth in protoplanetary disks with embedded planets I03 Brown dwarf atmospheres: the dust in the L – T transition region I04 Model Atmospheres of Substellar Atmospheres at a Young Age:Influence of Gravity and Dust I05 Detection of Planetary Transits using Wavelet Analysis and Genetic Algorithms I06 Automated Difference Imaging for Extrasolar Planet Searches I07 The formation of planets around stars with various masses I08 The Multiplicity of exoplanet host stars I09 Direct imaging of planets around young stars, the case of GQ Lup b I10 On the Nucleation of NH3 under the Atmospheric Conditions of Jovian‐like Planets I11 Unveiling a new low‐mass star formation site in NGC 1333 with SCUBA I12 Linear analysis of the stability of protoplanets: Possible planetary evolutions and comparisons to the Jeans‐analysis I13 Triggered planet formation in young stellar clusters I14 Convective Radiation Fluid‐Dynamics: Formation and Early Evolution at the Substellar Limit and Beyond  相似文献   

14.
In this paper we study the field of Kepler open cluster NGC 6866 using the data obtained from Kepler mission collected for a period of 4 years. We search for the red clump (RC) stars amongst the red giant (RG) stars showing solar-like oscillations using median gravity-mode period spacings (ΔP). We find a RG star KIC 8263801 having median gravity-mode period spacing 173.7 ± 6.4 s. We claim based on the median gravity-mode period spacing that KIC 8263801 is a secondary red clump (SRC) star which is massive enough to have ignited Helium burning in a non degenerate core. In the literature, no classification for KIC 8263801 has been provided. This is the first time that a star located in the field of NGC 6866 is classified in this manner.  相似文献   

15.
We present a search for the near-infrared spectroscopic signature of the close orbiting extrasolar giant planet HD 75289b. We obtained ∼230 spectra in the wavelength range 2.18–2.19 μm using the Phoenix spectrograph at Gemini South. By considering the direct spectrum, derived from irradiated model atmospheres, we search for the absorption profile signature present in the combined star and planet light. Since the planetary spectrum is separated from the stellar spectrum at most phases, we apply a phase-dependent orbital model and tomographic techniques to search for absorption signatures.
Because the absorption signature lies buried in the noise of a single exposure we apply a multiline deconvolution to the spectral lines available in order to boost the effective signal-to-noise ratio (S/N) of the data. The wavelength coverage of 80 Å is expected to contain ∼100 planetary lines, enabling a mean line with S/N of 800 to be achieved after deconvolution. We are nevertheless unable to detect the presence of the planet in the data and carry out further simulations to show that broader wavelength coverage should enable a planet like HD 75289b to be detected with 99.9 per cent confidence. We investigate the sensitivity of our method and estimate detection tolerances for mismatches between observed and model planetary atmospheres.  相似文献   

16.
The magnetic cataclysmic variable HU Aquarii displayed pronounced quasi‐periodic modulations of its eclipse timing. These were interpreted in terms of the light‐travel time (LTT) effect caused by a circumbinary planet or planetary system. We report new photometric observations that revealed another precise eclipse timing for the October 2013 epoch, the first obtained in a high accretion state after many years in low or intermediate states. The eclipse was observed to occur earlier by 95.3 ± 2.0 s or 62.8 ± 2.0 s than expected for an assumed linear or quadratic ephemeris, respectively. The implied apparent strong evolution of the orbital period calls for a revision of the current planetary model or the planetary parameters. The object deserves further monitoring to uncover the true nature of the observed variability and to constrain the properties of the proposed planet or planetary system. The new observations prove that advanced amateur equipment can successfully be used in the growing field of planet search in wide circumbinary orbits via the LTT effect. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

17.
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   

18.
We examine the possibility of detecting signatures of surviving Uranus/Neptune-like planets inside planetary nebulae. Planets that are not too close to the stars (orbital separation larger than ∼5 au) are likely to survive the entire evolution of the star. As the star turns into a planetary nebula, it has a fast wind and strong ionizing radiation. The interaction of the radiation and wind with a planet may lead to the formation of a compact condensation or tail inside the planetary nebula, which emits strongly in H α , but not in [O  iii ]. The position of the condensation (or tail) will change over a time-scale of ∼10 yr. Such condensations might be detected with currently existing telescopes.  相似文献   

19.
Numerical models dealing with the planetary scale differentiation of Mercury are presented with the short‐lived nuclide, 26Al, as the major heat source along with the impact‐induced heating during the accretion of planets. These two heat sources are considered to have caused differentiation of Mars, a planet with size comparable to Mercury. The chronological records and the thermal modeling of Mars indicate an early differentiation during the initial ~1 million years (Ma) of the formation of the solar system. We theorize that in case Mercury also accreted over an identical time scale, the two heat sources could have differentiated the planets. Although unlike Mars there is no chronological record of Mercury's differentiation, the proposed mechanism is worth investigation. We demonstrate distinct viable scenarios for a wide range of planetary compositions that could have produced the internal structure of Mercury as deduced by the MESSENGER mission, with a metallic iron (Fe‐Ni‐FeS) core of radius ~2000 km and a silicate mantle thickness of ~400 km. The initial compositions were derived from the enstatite and CB (Bencubbin) chondrites that were formed in the reducing environments of the early solar system. We have also considered distinct planetary accretion scenarios to understand their influence on thermal processing. The majority of our models would require impact‐induced mantle stripping of Mercury by hit and run mechanism with a protoplanet subsequent to its differentiation in order to produce the right size of mantle. However, this can be avoided if we increase the Fe‐Ni‐FeS contents to ~71% by weight. Finally, the models presented here can be used to understand the differentiation of Mercury‐like exoplanets and the planetary embryos of Venus and Earth.  相似文献   

20.
We carried out light curve solutions of the Kepler light curves of twenty detached eclipsing binaries with circular orbits and determined the orbital inclinations, temperatures. relative radii and luminosities of their components. We studied the quality of the solutions with respect to the adopted limb‐darkening law and its coefficients. The detailed tracing of the numerous and uninterrupted data of our targets gave us an unique possibility to detect and learn their spot and flare activity. We established that the out‐of‐eclipse variability of the most targets gradually changes from small‐amplitude two‐waved type to big‐amplitude one‐waved type and vice versa, i.e. their spot activity cycles pass through phase of two almost diametrically opposite spots and phase of big polar cool spot. We found that the low‐temperature targets show flare activity of UV Cet‐type with amplitudes of 0.002–0.22 mag and duration of up to several hours. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

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