We present new observations of the transiting system TrES-3 obtained from 2009 to 2011 at several observatories. The orbital parameters of the system were re- determined and a new linear ephemeris was calculated. The best quality light curve was used for light curve analysis, an other datasets were used to determine mid-transit times, Tc, and study transit time variation (TTV). For planet parameter determination we used two independent codes and finally, we concluded that our parameters are in agreement with previous studies. Based on our observations, we determined 14 mid-transit times. Together with published Tc we found that the timing residuals showed no significant deviation from the linear ephemeris. We concluded that a periodic TTV signal with an amplitude greater than 1 minute over a 4-year time span seems to be unlikely. Our analysis of an upper mass limit allows us to exclude an additional Earth-mass planet close to inner 3:1, 2:1, and 5:3 and outer 3:5, 1:2, and 1:3 mean-motion resonances. Using the long-term integration and applying the method of maximum eccentricity, the region from 0.015 au to 0.05 au was found unstable and the region beyond the 0.05 au was found to have a chaotic behaviour and its depletion increases with increasing values of the initial eccentricity as well as inclination.
The sdA problem - II. Photometric and Spectroscopic Follow-up
次矮星A星（英语：Subdwarf A star，sdA）是一种光谱分类法，用来描述具有富氢光谱和次主序星表面重力，但有效温度低于零年水平分支的天体。它们的进化起源是个谜。在这项工作中，我们讨论了选定的sdAs的后续观测结果。我们获得了24个对象的时间分辨光谱，和时间序列测光另外19个对象。对于两个目标，我们报告的光谱和光度观测。我们确认了七个新的极低质量白矮星（ELMs），其中一个是已知的食星。我们还发现了第八个成员的脉动榆树类。
High Resolution Spectroscopic Follow-up Observation Results for 13 EMP Candidates Selected by Narrow-band Photometry
Peking University（北京大学）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学天体物理中心）；University of Chinese Academy of Science（中国科学院大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Instituto de Física y Astronomía, Universidad de Valparaíso（瓦尔帕莱索大学物理与天文研究所）；Chinese Academy of Sciences South America Center for Astronomy (CASSACA), National Astronomical Observatories, CAS（中国科学院国家天文台南美天文中心）
