arXiv 0906.44822009-06-24astro-ph.SR

具有热的星周尘埃的后AGB星：低振幅增亮器的双星性

Post-AGB stars with hot circumstellar dust: binarity of the low-amplitude pulsators

Hans Van Winckel, Tom Lloyd Evans, Maryline Briquet, Peter De Cat, Pieter Degroote, Wim De Meester, Joris De Ridder, Pieter Deroo, Maarten Desmet, Rachel Drummo… 展开作者

Hans Van Winckel, Tom Lloyd Evans, Maryline Briquet, Peter De Cat, Pieter Degroote, Wim De Meester, Joris De Ridder, Pieter Deroo, Maarten Desmet, Rachel Drummond, Laurent Eyer, Martin A. T. Groenewegen, Katrien Kolenberg, David Kilkenny, Djazia Ladjal, Karolien Lefever, Thomas Maas, Fred Marang, Peter Martinez, Roy H. Østensen, Gert Raskin, Maarten Reyniers, Pierre Royer, Sophie Saesen, Katrien Uytterhoeven, Jan Vanautgaerden, Bart Vandenbussche, Francois van Wyk, Maja Vučković, Christoffel Waelkens, Wolfgang Zima

备注：: 13 pages, 15 figures, accepted for Astronomy and Astrophysics
DOI：: 10.1051/0004-6361/200912332

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摘要：

虽然第一个二元后AGB恒星是偶然发现的，但它们的光谱能量分布（SED）的独特特征使我们能够对双星进行更系统的搜索。我们选择了后AGB对象，显示了广泛的尘埃过剩往往已经开始在H或K，指出存在的引力约束尘埃盘在系统中。我们开始了一个非常广泛的多波长的研究，这些系统，在这里，我们报告我们的径向速度和光度监测结果的六颗星的早期F型，这是小振幅的放大器。为了确定低信噪比时间序列的径向速度，我们构造了专用的自相关掩模。对径向速度变化进行了详细分析，以区分脉动变化和轨道运动引起的变化。最后进行轨道最小化以约束轨道要素。所有六个物体都是双星，轨道周期从120天到1800天不等。五个系统有非圆形轨道。质量函数的范围从0.004到0.57太阳质量，伴星可能是初始质量（非常）低的未演化天体。我们认为，这些双星必须受到严重的双互动时，主要是一个冷的超巨星。虽然星周盘的起源还没有被很好地理解，但一般认为盘是在这个强相互作用阶段形成的。这些高度演化的天体的偏心轨道仍然知之甚少。与测量的轨道和质量函数，我们得出结论，环双星盘似乎有一个重大的影响，对一个显着的一部分双星系统的演变。

英文摘要：

While the first binary post-AGB stars were serendipitously discovered, the distinct characteristics of their Spectral Energy Distribution (SED) allowed us to launch a more systematic search for binaries. We selected post-AGB objects which show a broad dust excess often starting already at H or K, pointing to the presence of a gravitationally bound dusty disc in the system. We started a very extensive multi-wavelength study of those systems and here we report on our radial velocity and photometric monitoring results for six stars of early F type, which are pulsators of small amplitude. To determine the radial velocity of low signal-to-noise time-series, we constructed dedicated auto-correlation masks. The radial velocity variations were subjected to detailed analysis to differentiate between pulsational variability and variability due to orbital motion. Finally orbital minimalisation was performed to constrain the orbital elements. All of the six objects are binaries, with orbital periods ranging from 120 to 1800 days. Five systems have non-circular orbits. The mass functions range from 0.004 to 0.57 solar mass and the companions are likely unevolved objects of (very) low initial mass. We argue that these binaries must have been subject to severe binary interaction when the primary was a cool supergiant. Although the origin of the circumstellar disc is not well understood, the disc is generally believed to be formed during this strong interaction phase. The eccentric orbits of these highly evolved objects remain poorly understood. With the measured orbits and mass functions we conclude that the circumbinary discs seem to have a major impact on the evolution of a significant fraction of binary systems.

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