Accretion in the detached post-common-envelope binary LTT 560
Accretion in the detached post-common-envelope binary LTT 560
复制标题
分离后公共包络二进制 LTT 560 中的吸积
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
T. Ribeiro
中科院分区：
文献类型：
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作者：
C. Tappert;B. Gansicke;L. Schmidtobreick;T. Ribeiro
在以前的研究中，我们发现分离的后共包络双星LTT 560显示出由两个反相分量组成的Hα发射线。虽然其中一个明显是由次级晚型主序星星星的恒星活动造成的，但我们的分析表明，白色主星星星可能是第二个成分的起源。然而，数据的低分辨率意味着我们的解释仍然模糊不清。本文利用时间序列UVES数据比较了主星和次星的Hα辐射分量与金属吸收线的径向速度。我们发现，较弱的成分最肯定的起源于白色矮星，可能是由吸积。对白色矮星光谱的丰度分析得出的吸积率与恒星风引起的次级质量损失一致。第二个也是更强的Hα分量是由次级星星上的恒星活动引起的。由于在我们的时间分辨光谱学中出现了耀斑，所以很可能存在一个活跃的次级。此外，罗氏层析成像表明，次级星星的一个重要领域，其领先的一面和接近第一拉格朗日点是由星星斑点覆盖。最后，我们推导出系统的参数，并将其置于进化的背景下。我们发现，白色矮星是一个非常缓慢的旋转，这表明它有一个角动量的演变场白色矮星类似。我们预测，LTT 560将开始质量转移通过Rochelobe溢出在103.5 Gyr，并得出结论，该系统是目前人口的前身的代表性的激变变量。它很可能会演化成SU Uma型的矮新星。
In a previous study, we found that the detached post-common-envelope binary LTT 560 displays an Hα emission line consisting of two anti-phased components. While one of them was clearly caused by stellar activity from the secondary late-type main-sequence star, our analysis indicated that the white dwarf primary star is potentially the origin of the second component. However, the low resolution of the data means that our interpretation remains ambiguous. We here use time-series UVES data to compare the radial velocities of the Hα emission components to those of metal absorption lines from the primary and secondary stars. We find that the weaker component most certainly originates in the white dwarf and is probably caused by accretion. An abundance analysis of the white dwarf spectrum yields accretion rates that are consistent with mass loss from the secondary due to a stellar wind. The second and stronger Hα component is attributed to stellar activity on the secondary star. An active secondary is likely to be present because of the occurrence of a flare in our time-resolved spectroscopy. Furthermore, Roche tomography indicates that a significant area of the secondary star on its leading side and close to the first Lagrange point is covered by star spots. Finally, we derive the parameters for the system and place it in an evolutionary context. We find that the white dwarf is a very slow rotator, suggesting that it has had an angular-momentum evolution similar to that of field white dwarfs. We predict that LTT 560 will begin mass transfer via Rochelobe overflow in ∼3.5 Gyr, and conclude that the system is representative of the progenitors of the current population of cataclysmic variables. It will most likely evolve to become an SU UMa type dwarf nova.