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arXiv 2009.01669astro-ph.SR
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寻找主序星以外的亚恒星伴星的恒星脉动的定时

Timing of stellar pulsations to search for sub-stellar companions beyond the main sequence

F. Mackebrandt

备注：
PhD Thesis, 140 pages
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摘要：

恒星的大部分时间都在主序星（MS）上度过。但它们最实质性的变化发生在MS阶段之外，要么在MS前阶段之前，要么在MS后阶段之后。由于动力学过程的复杂多变，非MS星行星系统的演化与MS星行星系统有很大的不同。这项工作的重点是在后MS系统中寻找亚恒星伴星146，并确定其宿主恒星的演化状态，特别是亚矮星B星（sdB星）。正则模型涉及到双星演化来解释sdB星的存在。单一sdBs的形成情景更具争议性。除了两个氦白矮星的合并或其他明显的单一sdB星的合并过程外，另一种形成途径涉及行星系统。在红巨星阶段，恒星会与巨行星形成一个共同的包层，导致包层的丢失。因此，sdB恒星是测试行星如何生存并影响恒星演化后期阶段的实验室。sdB星的快速脉动可以用来检测从脉动最大值的预期到达时间的周期性变化的亚恒星同伴。这种计时方法对远距离的同伴特别敏感，并与其他系外行星探测方法互补。因此，计时方法开辟了一个新的参数范围内的主机恒星，并有助于了解单个sdBs的形成过程。在这项工作中，我实施，测试和应用的脉动时序分析，以寻找亚恒星的同伴在进化后期阶段的恒星系统。该方法已经在文献中建立，但是没有达到能够自动处理高节奏数据的长时间序列的程度，即，来自太空的观测

英文摘要：

(abridged) Stars spend most of their life on the main sequence (MS). But their most substantial changes occur off the MS stage, either before on the pre-MS or beyond at the post-MS phase. Due to very complex and varied dynamical processes, the evolution of planetary systems orbiting non-MS stars significantly differs from those of MS planetary systems. This work focusses on the search for sub-stellar companions in post-MS systems146 and determination of the evolutionary state of their host stars, especially subdwarf B stars (sdB stars). The canonical model involves binary evolution to explain the existence of sdB stars. Formation scenarios for single sdBs are more controversially discussed. Besides the merger of two helium white dwarfs or other merger processes for apparently single sdB stars, an alternative formation channel involves planetary systems. During the red giant phase, the star would develop a common envelope w146ith a giant planet that leads to the loss of the envelope. Thus, sdB stars are laboratories to test how planets survive and influence the late phases of stellar evolution. The rapid pulsations of sdB stars can be used to detect sub-stellar companions from periodic variations in the expected arrival times of the pulsation maxima. This timing method is particularly sensitive to companions at large distances and complementary to other exoplanet detection methods. Thus, the timing method opens up a new parameter range in terms of the host stars and helps to understand the formation process of single sdBs. In this work I implemented, tested and applied the pulsation timing analysis to search for sub-stellar companions in late evolutionary stage stellar systems. The method is already established in the literature but not to an extent which is capable of automatically processing long-time series of high-cadence data, i.e., from space born observations.

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