Spectroscopic monitoring of bright, oscillating Algol-type stars

类oEA星由食大陵型系统与质量转移的质量吸积的主要表现出三角洲盾状振荡。这些系统是进行小行星地震研究的特殊物体，因为它们允许对质量转移事件期间的短期动态恒星演化进行调查，质量转移事件最有可能是由质量较小的次级恒星的磁活动周期引起的。冷次级的磁循环之间的相互作用的基本原理，快速传质事件的发生，系统的动力学行为，以及质量增加的主要组件的不同非径向脉动模式的激励可以非常详细地研究。分析oEA星的优势在于它们是食双星。这使我们能够从组合的光度-光谱分析中获得精确的恒星和系统参数。非径向脉动模式的识别被简化了，这是由于在日食期间次级恒星对振荡的主成分盘的扫描而产生的空间过滤效应。本提案的目的是得出对关键oEA星星RZ Cas和TW Dra和AS Eri的较短时间序列的15年国际光谱和光度监测的最终结果，并从我们的国际团队近年来的观测中获得新的结果。我们希望使用最先进的方法来调查大量收集的数据，特别是我们希望在本项目框架内开发的改进的最小二乘反卷积方法。这将使我们能够将高分辨率复合光谱的时间序列分解成各个分量的光谱的时间序列，而不会丢失关于固有振荡信号的信息。我们的分析将包括精确的恒星和系统参数的确定，快速质量转移的情节，包括在不同时期的观测质量转移率的计算，识别非径向脉动模式，第一次，oEA星的活动和非活动阶段的asteroseisic建模搜索。将比较不同方法的结果，包括3D流体动力学模拟。最后，我们希望建立一个一致的图片所造成的所有恒星和系统参数的变化，如轨道和旋转周期，质量转移率，激发的非径向脉动模式的频率和振幅的冷次要组件的磁循环。所得结果将有助于澄清有关磁活动在大陵型恒星中的作用以及其组成部分之间的质量和角动量转移的问题。

The class of oEA stars consists of eclipsing Algol-type systems with mass transfer where the mass-accreting primary shows delta Scuti-like oscillations. These systems are extraordinary objects for asteroseismic studies since they allow for an investigation of short-term dynamical stellar evolution during mass-transfer episodes, most probably caused by the magnetic activity cycle of the less massive secondary. Basic principles of the interaction between the magnetic cycle of the cool secondary, the occurrence of rapid mass-transfer episodes, the dynamical behavior of the system, and the excitation of different non-radial pulsation modes of the mass-gaining primary component can be studied in great detail. Advantages for the analysis of oEA stars follow from the fact that they are eclipsing binaries. This enables us to derive precise stellar and system parameters from the combined photometric-spectroscopic analysis. The identification of non-radial pulsation modes is simplified by the spatial filtration effect that occurs due to the scanning of the disk of the oscillating primary component by the secondary during the eclipses.The aim of this proposal is to derive the final results of 15 years of international spectroscopic and photometric monitoring of the key oEA star RZ Cas and of shorter time series of TW Dra and AS Eri, and to get new results from recent years of observations obtained by our international team. We want to use state-of-the-art methods for the investigation of a huge amount of collected data, in particular an improved method of least squares deconvolution that we want to develop in the framework of this project. It will enable us to decompose the time series of high-resolution composite spectra into time series of spectra of the individual components without losing information about the intrinsic oscillation signals. Our analysis will comprise the determination of precise stellar and system parameters, the search for episodes of rapid mass transfer including the calculation of mass-transfer rates during different epochs of observation, the identification of non-radial pulsation modes and, for the first time, an asteroseismic modeling of the oEA stars in active and inactive phases. The results from different methods, including 3D-hydrodynamic simulations, will be compared. Finally, we want to establish a consistent picture of the changes in all stellar and system parameters caused by the magnetic cycle of the cool secondary component, like orbital and rotation period, mass-transfer rate, and frequencies and amplitudes of the excited non-radial pulsation modes. The obtained results will help to clarify the questions about the role of magnetic activity in Algol-type stars and about the kind of mass and angular momentum transfer between their components.