恒星磁活动与冷矮星中的岩石行星
Stellar magnetic activity and rocky planets in cool dwarf stars
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中文总结 AI 辅助
针对M矮星恒星活动干扰径向速度行星探测的问题，本论文采用高斯过程建模，结合高精度光谱与测光数据，实现了行星信号与恒星活动的稳健分离，为探测岩石行星提供了有效方法。
中文摘要 AI 辅助
系外行星天文学已进入黄金时代，迄今为止人类已发现超过6000颗系外行星。这些发现大多是通过凌星测光法和径向速度（RV）技术实现的。虽然凌星巡天在发现数量上领先，但RV方法在系外行星科学中仍然是至关重要且不可或缺的技术，尤其是在最普遍的恒星族群——M矮星中。M矮星质量低，使其成为理论上RV探测的首选目标，因为相同周期下系外行星信号更强，因此更容易被探测和精确测量。然而，M矮星表现出的恒星活动带来了重大挑战，尤其是在寻求约1 m/s或更低的RV半振幅时。已知恒星活动会模拟或抑制行星信号，其效应在所有时间尺度上都有体现：从对流运动引起的短时信号（持续数分钟至数天），到恒星表面的活动区（数天至数月），再到长期磁周期（数年至数十年）。这些问题凸显了对稳健方法的迫切需求，这些方法能够可靠地将恒星变化与真实行星信号分离。本博士论文通过应用高斯过程（GP）建模来探索这些挑战。我展示了三项不同但相互关联的研究，其中两项将高精度光谱学和测光法与统一的基于GP的方法相结合，从而能够稳健地将行星信号与恒星活动分离。这三项研究共同说明了如何将不同来源的观测数据与适当的统计工具相结合，以探测系外行星，并有可能解释恒星活动。
英文摘要
Exoplanetary astronomy has entered its Golden Age, with humanity having found over 6000 exoplanets to date. The majority of these discoveries have been achieved through transit-photometry and radial-velocity (RV) techniques. While transit surveys lead in discovery numbers, the RV method persists as a vital and indispensable technique in exoplanetary science, particularly in the most prevalent stellar population -- M dwarfs. Their low masses make them the theoretical favourites for RV detections, since exoplanet signals are stronger over the same period, and are therefore easier to detect and measure accurately. Nevertheless, the stellar activity M dwarfs exhibit introduces significant challenges, particularly when seeking RV semi-amplitudes to the order of 1 m$\,$s$^{-1}$, or lower. Stellar activity is known to mimic or suppress planetary signals, and its effects manifest across all time scales: from short-lived signals due to convective motion (lasting minutes to days), through active regions on the stellar surface (days to months), to long-term magnetic cycles (years to decades). These issues highlight the urgent need for robust methodologies that are capable of reliably disentangling stellar variability from genuine planetary signals. This doctoral dissertation explores these challenges through the application of Gaussian-process (GP) modelling. I present three distinct but interconnected publications that integrate high-precision spectroscopy and photometry with a unified GP-based approach in two cases, and that enable robust disentanglement of planetary signals from stellar activity. Together, these three studies illustrate how observations of different origin can be combined with appropriate statistical machinery for the sake of detecting exoplanets, with the possibility of interpreting stellar activity.
