基于CHES卫星的模拟观测与轨道反演

Observation Simulation and Orbital Retrieval of the CHES Satellite

迄今为止,视向速度法与凌星法发现了绝大多数系外行星,天体测量法与之相比在行星轨道参数和质量确定等方面具有独特优势.近邻宜居行星巡天计划(Closeby Habitable Exoplanet Survey,CHES)拟基于微角秒级空间天体测量方法搜寻太阳系近邻(距离太阳约10 pc)的100颗类太阳型恒星周围的宜居带类地行星;开展近邻行星系统的全面普查,获取行星真实质量和三维轨道参数,建立完备的近邻系外行星数据库.基于CHES卫星的观测模式与科学目标,针对Alpha Centauri A、模拟太阳系系统、51 Peg与黑洞Cyg X-1进行了模拟观测,生成了天体测量仿真数据,使用Lomb-Scargle与贝叶斯信息准则(Bayesian information criteria,BIC)两种周期谱分析行星轨道周期信号,并采用Markov Chain Monte Carlo(MCMC)算法对行星系统进行轨道反演,获得的结果与行星初始参数吻合.进一步讨论了参考星周围存在的巨行星对于宜居行星探测的影响,利用BIC周期谱方法可识别周围可能存在行星的参考星.

So far,most of the exoplanets have been discussed with the radial velocity and transient methods,in comparison with these detection techniques,the astrometric method has unique advantages in the determination of planetary orbital parameters and masses.Closeby Habitable Exoplanet Survey(CHES)will search for terrestrial planets in the habitable zone around 100 sun-like stars in the solar system’s neighbors(about 10 pc from the sun)using the micro-arcsecond space astrometry method,and further carry out a comprehensive census of nearby planetary systems to obtain the true mass of planets and three-dimensional orbital parameters to establish a complete database of the nearby planetary systems.Based on the observation mode and scientific objectives of the CHES satellite,this work conducted the simulated observations on Alpha Centauri A,a simulated solar system,51 Peg,and the black hole Cyg X-1,and generated astrometric simulation data,using two periodic spectra of Lomb-Scargle and BIC(Bayesian information criteria).The signal of the planetary orbit period is analyzed,and the orbit inversion of the planetary system is carried out with the Markov Chain Monte Carlo(MCMC)algorithm.In addition,this work further discusses the influence of the planets around the reference stars on the detection of habitable planets,and the BIC periodic spectrum can be used to identify the reference stars that may have planets around them.