Circumbinary planets from space-based transiting planet surveys

围绕恒星倍数运行的行星是一个流行的科幻小说的比喻，但是，虽然在1995年就证实了第一颗围绕类太阳恒星运行的系外行星的发现，但第一颗环双星行星直到2011年才宣布。自宣布以来，通过凌日探测，日食计时和微透镜，已经发现了其他环双星行星（或CBPs），但与已知系外行星的总数相比，已知CBPs的数量仍然非常少。这限制了我们研究CBP系统形成和演化的能力，这可能与单恒星行星系统的类似过程非常不同。已知CBPs的数量有限也限制了我们对潜在参数分布的了解，并且当前的样本受到强烈的观测偏差的影响。大多数已知的凌日CBPs都是由美国宇航局的开普勒任务发现的，但自从开普勒任务不幸失败以来，搜寻工作一直由美国宇航局的TESS卫星接手，该卫星最近有了一些新发现。在未来，ESA的PLATO任务也有可能探测到新的cbp，并扩大我们对这些有趣系统的样本。然而，与单星系统相比，探测凌日的环双星需要更多的偶然时机。不仅行星的凌日与恒星的日食相比相形见绌，而且主双星和轨道行星之间的引力相互作用导致了快速的轨道进动。因此，事实上，几乎所有目前已知的过境cbp都将在某一时刻停止过境。然而，这个过程是周期性的，只要时间足够长，所有星体最终都会再次凌日。这也意味着以前未过境的CBPs可能出现在明显没有行星的食双星周围。这个项目将探索环绕双星的迷人世界，重点是利用天基天文台的数据来研究那些经过一颗或两颗主星的行星。该项目将从TESS对食双星的观测中寻找环绕双星的候选行星开始。这些可能是有许多可探测到的凌日的短周期行星，或者是单一的凌日事件，表明行星的轨道与它们的主双星不一致，甚至是通过日食时间变化检测到的非凌日CBPs。在确定候选CBPs之后，将对其进行建模，以对其特征进行初步估计并预测其未来的演变，并寻求进一步的观察来确认候选CBPs是真实存在的，并改进其特征。进一步的工作途径可能包括将搜索扩展到开普勒和K2的数据，或模拟CBP系统，以评估它们的可探测性，并限制行星存在于已知的食双星系统中的可能性。还可以利用模拟数据探索优化CBPs检测和分析的方法，以及PLATO的潜在CBPs产量。

Planets orbiting stellar multiples are a popular science fiction trope, but while detection of the first exoplanet around a Sun-like star was confirmed in 1995, the first circumbinary planet was only announced in 2011.Since that announcement other circumbinary planets (or CBPs) have been found through transit detection, eclipse timing, and microlensing, but the number of known CBPs is still very small compared to the total number of known exoplanets. This limits our ability to investigate the formation and evolution of CBP systems, which may be very different from the similar processes for single-star planetary systems. The limited number of known CBPs also restricts our knowledge of the underlying parameter distributions, and the current sample is affected by strong observational biases.Most of the known transiting CBPs were discovered by NASA's Kepler mission, but since that mission's unfortunate demise the search has been taken up by NASA's TESS satellite, which has produced some recent new discoveries. In the future, ESA's PLATO mission is also likely to detect new CBPs and expand our sample of these interesting systems.However, detection of a transiting circumbinary requires more fortuitous timing than is the case for single-star systems. Not only are the planet's transits dwarfed by the stellar eclipses, but the gravitational interactions between the host binary stars and the orbiting planet lead to rapid orbital precession. Thus, nearly all of the currently known transiting CBPs will, in fact, cease transiting at some point. The process is periodic, however, and given long enough all will eventually transit once more. This also means that previously non-transiting CBPs may appear around apparently planetless eclipsing binaries.This project will explore the fascinating world of circumbinary planets, focusing on the use of data from space-based observatories to study those that transit one or both of their host stars. The project will start by searching for circumbinary planet candidates in TESS observations of eclipsing binaries. These could be short-period planets with many detectable transits, or single-transit events indicative of planets on orbits misaligned with their host binary, or even non-transiting CBPs detected through eclipse timing variations. Following their identification, candidate CBPs will be modelled to produce preliminary estimates of their characteristics and predict their future evolution, and further observations will be sought to confirm that the candidates are real and improve their characterisation. Further avenues of work could include extension of the search to data from Kepler and K2, or simulation of CBP systems to evaluate their detectability and constrain the likelihood of planets being present in known eclipsing binary systems. Methods for optimising detection and analysis of CBPs, and the potential yield of CBPs from PLATO, may also be explored using simulated data.