| The discovery of the first exosolar planet at the end of the 20th century has granted the thousand-year-old subject astronomy a new research field. Undoubtedly, the detec-tion and study of exoplanets is now one of the hottest research directions in modern astronomy. Detecting by measuring the radial velocity of host stars used to be almost the only fruitful detection method in the earlier days of exoplanet detection. Photomet-ric measurement of transiting exoplanets, however, is now widely favored due to its high efficiency. Moreover, planets discovered by transit method are able to provide us with more comprehensive information, making the understanding of the characteristics and the evolutionary process of exoplanets deepen.To effectively detect exoplanets, it is vital to have high-precision, wide-field-of-view (FOV), and continuous photometry. Besides extremely costly space telescope programs such as the Kepler spacecraft, which is specially designed for detecting transiting exoplanets, superior photometric conditions and long polar nights in Antarc-tica provide us with a new possible solution for continuous high-precision photometric observation.To take advantage of the extraordinary astronomical observing conditions on Dome A, Antarctica, the Chinese Small Telescope Array (CSTAR) was installed on Dome A to carry out time-domain observations. The CSTAR facility consists of 4 telescopes, each with a diameter of 14.5 cm, pointing at the south celestial pole. During the polar nights of 2008,4 months of continuous observation of nearly 20,000 stars in an area of 20 deg2 around the south celestial pole was performed by the CSTAR telescope. On the basis of the acquired data, transiting exoplanet and variable detection research were carried out.As the fruitful results of exoplanet detection accumulate gradually, main research focus in the exoplanet field has shifted from mere detection to the parallel advancement of detection and characterizing. We, therefore, set up a follow-up program to charac-terize known transiting exoplanets using some of the 1-meter telescopes in China.This paper will introduce our work on detecting transiting exoplanets and vari-ables near the south celestial pole using the CSTAR telescope and the follow-up re-searches on known transiting exoplanets in detail.In the first chapter, we will start from introducing the history of exoplanet de-tection and popular detection methods, then move on to the general summary of the diversity of detected planets. During this process, we will be looking at some of the fascinating yet still unanswered problems in the exoplanet field, which leads to our efforts on solving these problems by detecting exoplanets using the CSTAR telescope and by conducting follow-up studies on the known transiting exoplanets.The second chapter will mainly focus on introducing the instrumentation, obser-vation of CSTAR, and the previous data reduction process. After these, we will go deeply into describing the methods we adopted in correcting multiple dominant sys-tematic errors in the CSTAR data, in order to increase photometric precision.The CSTAR facility has an FOV of about 20 deg2. The extinction across such a large FOV is non-uniform, especially under bad weather conditions. Systematic errors would have been artificially brought in if the same photometric calibration is done within the whole FOV. To avoid such error, each frame is compared with the master reference frame which is constructed by combining 10,000 frames taken under the best photometric conditions. This allows us to achieve the local extinction conditions, with the help of which photometric calibration of every frame is improved.CSTAR is a static telescope with its view fixed on the south celestial pole. The diurnal motions of the stellar images on the CCD plane bring the residual error of the correction of flat-field into photometry. This error is corrected by comparing each star with a stable and bright reference star on its diurnal motion path. Photometric precision after this step improves significantly.The resulting photometric precision reaches 4 mmag for the brightest unsaturated star, which is adequate for detecting exoplanets and low-amplitude variables.In the third chapter, we will introduce our work on the detection and confirmation of transiting exoplanets from the CSTAR 2008 data set. We first use the popular search-ing algorithm Box-fitting Least Square (BLS) to look for possible transiting events. We then exclude a large number of false alarm signals by thorough statistical analysis and visual inspection based on the features of the selected light curves and the characteris-tics of their host stars. Eventually, utilizing spectrum and RV follow-up observations, we confirm 6 transiting exoplanet candidates with very high likelihood. These can-didates are now being confirmed using the high-precision RV data acquired by the Australian-Anglo 3.9 m telescope. These are the first transiting exoplanet candidate discovered in China, and the first candidates detected with Antarctic transit survey.In the fourth chapter, our work on detecting and classifying variables found in the CSTAR 2008 data will be introduced. In this work, we apply two commonly used methods - light curve variation evaluation (mag-rms relation, Stetson J index) and periodicity analysis - and detected 274 variables in the CSTAR 2008 data set,83 among which are our original discovery. The classification of all 274 detected variables is then completed based on the characteristics of their light curves and by referring to stellar parameters provided by other sky surveys.108 out of 274 variables are classified for the first time.The Transit Exoplanet Monitoring Project (TEMP) and its first scientific results will be expounded in the fifth chapter. Follow-up observations on known transiting planetary systems using ground-based telescopes enable us to improve the system pa-rameters and the transit ephemerides of known exoplanets, as well as to confirm long-period transiting exoplanet candidates. The possibility of the existence of undetected planets within known planetary systems could be evaluated by the Transit Timing Vari-ations (TTV) method, which is also able to confirm planets and measure their masses in multiple-transiting systems. As the first result of the TEMP project, our efforts on carrying out follow-up observations of the hot Jupiter system HAT-P-29 for the first time after its detection attained 6 high-precision light curves, with which we refined its orbital parameters and corrected its transit ephemeris. Based on the analysis of TTV of HAT-P-29b, we constrained the possibility of the existence of other planets around HAT-P-29 by dynamical simulations.At last, in the sixth chapter, I will summarize the main works I have completed during my doctoral study, and look forward to using photometric and Doppler veloc-ity data to help constrain and understand some of the long-term yet still unanswered problems in the exoplanet field, such as the composition of super Earths, the domi-nant migration process of hot Jupiters from outside the snow line to the position they are now, the possible existence of low-mass planets around hot Jupiters, the origin of the spin-orbit misalignment in hot Jupiter systems, the relation between lack of short-period planets in the solar system and the existence of Jupiter, and furthermore, how do we understand the unique configuration we deem our solar system to be in modern ideas among the exoplanet population?... |
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