Spectroscopic modeling of oscillating Algol-type stars I. RZ Cassiopeia
Spectroscopic modeling of oscillating Algol-type stars I. RZ Cassiopeia
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振荡大陵五型恒星 I. RZ 仙后座的光谱模型
DOI：
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发表时间：
2009
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通讯作者：
D. Mkrtichian
中科院分区：
文献类型：
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作者：
A. Tkachenko;H. Lehmann;D. Mkrtichian
目标。基于高分辨率光谱的时间序列，我们研究了OEA星(即具有振荡主分量的Algol型食双星)RZ Cas，以获得精确的系统和大气参数，并在不同的观测时期寻找快速质量传递的相及其对各种系统参数的影响。方法：研究方法。我们结合了多种方法，包括用于分解光谱分量和确定轨道解的KELEL程序，用于通过基于大气模型的合成光谱计算来分析解缠光谱的SynthV程序，以及新开发的程序Shellspec07_Inverse，用于从所有轨道相的复合线轮廓计算优化的恒星参数。结果。根据2006年拍摄的光谱，假设只有两颗恒星存在，就可以准确地模拟RZ Cas系统。对于2001年获得的光谱，我们通过在初级光谱周围添加一个光衰减吸积环来获得改进的解，但无法模拟O-C值分布中的剩余结构。RZ Cas的主星是一颗正常的A型恒星，没有显示λBOO信号，两个分量都接近太阳丰度。主部件的派生质量和部件的分离比先前假设的略小。基元的有效温度为8900K，比以前的计算结果提高了300K。据推测，充填罗氏叶的次生岩在其表面有一个指向原生岩层的大冷点。我们证实了2001年至2006年间的轨道周期增加了2个S，而不是先前假设的轨道径向速度幅度的减小。结论。利用新的Shellspec07_Inverse程序，我们得到了RZ Cas的精确恒星参数。结果清楚地表明，RZ-Cas在2001年发生了快速传质的瞬变阶段，而在2006年，该系统处于安静状态。
Aims. Based on time series of high-resolution spectra, we investigate the oEA star (i.e., Algol-type eclipsing binary with an oscillating primary component) RZ Cas to derive precise system and atmospheric parameters and search for phases of rapid mass-transfer and its effects on various system parameters at different epochs of observations. Methods. We combine a variety of methods including the KOREL program to decompose the components of the spectra and determine the orbital solution, the SynthV program to analyze the disentangled spectra by computing synthetic spectra based on atmosphere models, and the newly developed program Shellspec07_inverse to compute optimized stellar parameters from composite line profiles at all orbital phases. Results. Based on spectra taken in 2006, the RZ Cas system can be modeled accurately by assuming that only two stars are present. For spectra acquired in 2001, we obtained an improved solution by adding a light attenuating accretion annulus surrounding the primary, but were unable to model remaining structures in the O–C value distribution. The primary of RZ Cas is a normal A-type star that shows no λ Boo signatures, both components have close to solar abundance. The derived mass of the primary and the separation of the components are slightly smaller than previously assumed. The effective temperature of the primary of 8900 K, is 300 K higher than derived before. The Roche-lobe-filling secondary is assumed to have a large cool spot on its surface pointing towards the primary. We confirm the increase in the orbital period by 2 s between years 2001 and 2006, but not the previously assumed decrease in the orbital radial velocity amplitudes. Conclusions. With the new Shellspec07_inverse program, we obtained precise stellar parameters of RZ Cas. Results clearly point to the occurrence of a transient phase of rapid mass transfer of RZ Cas in 2001, while in 2006 the system was in a quiet state.