| 其他摘要 | Since the discovery of the first extrasolar planet orbiting a Sun-like star in 1995, more than3,700 extrasolar planets have been discovered with the development of many ground-basedand space-based exoplanet-hunting projects. In addition, Kepler mission has also detectedmore than 4,400 exoplanet candidates with the help of transit method. The study of extrasolarplanetary systems can help us to understand the formation and evolution of our Solar system, aswell as search for Earth-like planets in the habitable zone and life outside our Solar system. Injust two decades, the study of extrasolar planets has become an important field of astrophysics.As a special type of extrasolar planetary system, the transiting exoplanetary system ischaracterized by its periodic transit events. Through the photometric observation of transitevents, we can not only obtain the physical parameters and planetary properties, but also confirmand characterize the discovered but unproven planetary candidates, as well as detect theundiscovered planetary bodies in the system. In addition, these fundamental physical parametersprovide an important cornerstone for the study of the structure, formation and dynamicevolution of exoplanets. Therefore, we carried out a series of follow-up observations for sometransiting exoplanetary systems detected by several ground-based transit survey projects, suchas SuperWASP, HATNet and so on. At the same time, we are also exploring and characterizingexoplanetary systems discovered by Kepler mission. From 2010 to 2015, we carried out photometric observations for eleven transit events oftransiting exoplanetary system HAT-P-20 by using the 1m and 2.4m telescopes of Yunnan Observatories of Chinese Academy of Sciences, the 0.5m telescope of Ho Koon Nature Educationcum Astronomical Centre in China and the 0.3m telescope in Spain. Using the standard IRAFroutine, the photometric images were reduced, and the systematic errors in the light curveswere corrected. In addition, we also collected the light curves and radial velocity curves availablein the literatures. Due to the strong magnetic activity on the surface of the host star of thesystem, these transit light curves su er varying distortions from spots of host star HAT-P-20.In order to accurately analyze these light curves, we developed the Spot and Transit ModelingTool (STMT), which can efficiently simulate multiple transit events and spot-crossing eventsof a spotted host star. With the help of STMT, we obtain more accurate system parameters andtransit times of HAT-P-20, and confirm that the significant TTV signal found by the previousresearch is induced by the strong magnetic activity of the host star rather than the gravitationalperturbation from any undetected body in the system. By investigating the exoplanetary systems detected by Kepler mission, we find that thekepler-411 is a comparatively valuable system. It is shown in :(1) based on the photometricdata of Kepler-411 collected by Kepler mission, the transit-like signals may be induced by threeplanet candidates, but only two signals were confirmed to be transit events of two exoplanetsorbiting Kepler-411. (2) only the unconfirmed transit-like signals show a significant TTV, andthe amplitude of the TTV reaches up to about 50 minutes. (3) the periods of these transitingbodies do not show any commensurability, that is, two planets and one planetary candidateare not in or near the mean motion resonances (MMR), in which the TTV signals induced bygravitational interactions between planets are amplified. Through comprehensively analyzingthe photometric data and newly measured TTV, we confirm that the transit-like signals areinduced by a transiting planet orbiting kepler-411, and detect a non-transiting planet which iscloser to 1:2 MMR with the third transiting planet. Based on the analysis of the measured radiiand masses, we find that the innermost planet is a rocky planet, while the outer two planets bothhave gaseous envelope besides the massive core. Finally, numerous dynamic simulations showthat transiting exoplanetary system Kepler-411 could run stably at least 1 Myr. |
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