Detection, Confirmation and Characterization of Multi-planet Systems by Transit Time Variations

通过传输时间变化检测、确认和表征多行星系统

• 批准号: 362567553
• 负责人: Privatdozent Dr. Martin Pätzold
• 金额: --
• 依托单位: Rheinisches Institut für Umweltforschung (EURAD)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/362567553?language=en
• 关键词: Detection; Confirmation; Characterization; Multi; planet

Multi-planet systems are crucial for the understanding of the formation and dynamical evolution of planetary systems. Only a small number of confirmed planets with true masses is known (compared to the number of all planetary candidates) because there is not enough telescope time available to cover all pending confirmations, in particular for faint stars. The mass determination for Earth- or Neptune-sized planets by radial velocity (RV) is in particular difficult with current telescopes and instrumental technique because of their small gravitational influence onto their host star. Thus it is not expected to get masses from all planetary candidates covering the full radii and orbital period ranges. Another method to characterize the planetary system and to complete this sample with regard to longer periods is the Transit Time Variation (TTV). This method uses only the information from the light curve and can detect, confirm and characterize transiting as well as non-transiting planets in multi-planet systems.Are there more undetected planets in a system? How closely packed are these systems? These questions may be answered by studying the orbital evolution of multi-planet systems: How do the orbital eccentricity and semi-major axis change with time? What are the influences of tides and general relativity on extremely short period TTV-planets? In recent TTV studies and in all existing TTV analysis software tools only the gravitational force is considered. This simplification may be valid for the majority of the analyzed systems but not for all. The inclusion of other forces is crucial for close-in planets (tides, general relativity), planets orbiting close to each other (planet-planet interaction) and for non-transiting planets perturbing the known transiting planet. By analyzing and comparing all forces together, the knowledge of the orbit, the stellar mass, the masses of the transiting planet and the perturbing planet may be verified and/or improved in particular for candidates difficult to be verified by RV observations. The questions above shall be answered by the analysis of light curves from existing planetary systems showing TTV as well as the search for more systems with TTV in ´new´ light curves from the Kepler and K2 missions. The already existing software package developed at RIU-PF shall become fully automated by implementing a Monte Carlo Markov Chain to search the whole parameter space for the best solution. Tides, general relativity and stellar oblateness shall be implemented in the orbit simulation for a full characterization of the planetary system. TTV is mostly the only chance to characterize a detected planetary system. The direct application, however, is the verification of transiting planets independent from ground-based observations. In consequence, TTV is also the detection of an unknown planet perturbing the known planet and therefore the detection of a multi-planet system which can be directly characterized by TTV.

多行星系统对于理解行星系统的形成和动力学演化至关重要。只有一小部分被确认的行星具有真正的质量（与所有行星候选者的数量相比），因为没有足够的望远镜时间来覆盖所有待确认的行星，特别是对于暗淡的恒星。用径向速度（RV）测定地球或海王星大小的行星的质量，特别是用现有的望远镜和仪器技术，因为它们对宿主星星的引力影响很小。因此，它不可能从所有覆盖整个半径和轨道周期范围的候选行星中获得质量。另一种描述行星系统特征并在较长周期内完成此样本的方法是渡越时间变化（TTV）。这种方法只使用光变曲线的信息，可以检测、确认和表征多行星系统中的凌日和非凌日行星。这些系统有多紧密？这些问题可以通过研究多行星系统的轨道演化来回答：轨道偏心率和半长轴是如何随时间变化的？潮汐和广义相对论对极短周期TTV行星有何影响？在最近的TTV研究和所有现有的TTV分析软件工具中，只考虑重力。这种简化可能对大多数分析系统有效，但不是对所有系统都有效。包含其他力对于近距离行星（潮汐，广义相对论），行星轨道彼此靠近（行星-行星相互作用）以及非凌日行星扰动已知凌日行星至关重要。通过一起分析和比较所有力，可以验证和/或改进轨道、恒星质量、过境行星和扰动行星的质量的知识，特别是对于难以通过RV观测验证的候选者。上述问题将通过分析显示TTV的现有行星系统的光变曲线以及在Kepler和K2任务的“新”光变曲线中寻找更多具有TTV的系统来回答。RIU-PF开发的现有软件包应通过实施蒙特卡洛马尔可夫链来搜索整个参数空间以获得最佳解决方案，从而实现完全自动化。潮汐、广义相对论和恒星扁率应在轨道模拟中加以实施，以便充分描述行星系统的特征。TTV通常是描述探测到的行星系统的唯一机会。然而，直接的应用是独立于地面观测的凌日行星的验证。因此，TTV也是一个未知行星扰动已知行星的探测，因此可以直接用TTV来表征多行星系统。