Spectroscopic time-series analysis of R Canis Majoris
Spectroscopic time-series analysis of R Canis Majoris
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DOI：
10.1051/0004-6361/201629914
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发表时间：
2018-04
影响因子：
6.5
通讯作者：
H. Lehmann;V. Tsymbal;F. Pertermann;A. Tkachenko;D. Mkrtichian;N. A-thano
中科院分区：
文献类型：
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作者：
H. Lehmann;V. Tsymbal;F. Pertermann;A. Tkachenko;D. Mkrtichian;N. A-thano
大犬R星是一小群大人猿型恒星的原型，它们的轨道周期短，质量比低。先前在其光曲线中发现的短期振荡尚未得到证实。我们研究了一个新的高分辨率光谱时间序列，目的是得出改进的恒星和系统参数，寻找观测光谱中第三个成分可能的影响，寻找大耳座系统活动的迹象，并寻找径向速度的短期变化。我们将复合光谱分解为二元组分的光谱。然后我们分析了这两颗恒星的高信噪比光谱。使用基于改进的最小二乘反褶积方法的新开发的程序代码，我们能够确定初食期间两个分量的径向速度。这使我们能够建立一个更好的系统模型，包括罗西特-麦克劳克林效应，并得出改进的轨道参数。结合光谱分析的结果，我们得到了精确的恒星和系统参数。我们进一步推导出至少一个21.38 c d−1的振荡频率。它只能在初食期间被探测到，并证实了之前的光度发现。结果表明，由于日食映射效应，非径向脉动模式的振幅放大。光谱中He - I线的存在表明在rcma系统中存在传质现象。它的罗氏几何计算提供了证据，表明冷次级分量可能填充它的罗氏叶。在观测到的光谱中没有发现系统中存在第三个天体的证据。
R Canis Majoris is the prototype of a small group of Algol-type stars showing short orbital periods and low mass ratios. A previous detection of short-term oscillations in its light curve has not yet been confirmed. We investigate a new time series of high-resolution spectra with the aim to derive improved stellar and system parameters, to search for the possible impact of a third component in the observed spectra, to look for indications of activity in the Algol system, and to search for short-term variations in radial velocities. We disentangled the composite spectra into the spectra of the binary components. Then we analysed the resulting high signal-to-noise spectra of both stars. Using a newly developed program code based on an improved method of least-squares deconvolution, we were able to determine the radial velocities of both components also during primary eclipse. This allowed us to develop a better model of the system including the Rossiter–McLaughlin effect and to derive improved orbital parameters. Combining the results with those from spectrum analysis, we obtain accurate stellar and system parameters. We further deduce at least one oscillation frequency of 21.38 c d−1. It could be detected during primary eclipses only and confirms a previous photometric finding. Results point to an amplitude amplification of non-radial pulsation modes due to the eclipse mapping effect. The presence of a He I line in the spectra indicates mass transfer in the R CMa system. Calculations of its Roche geometry give evidence that the cool secondary component may fill its Roche lobe. No evidence of a third body in the system could be found in the observed spectra.