The destructive effects of binary encounters on red giants in the Galactic Centre
The destructive effects of binary encounters on red giants in the Galactic Centre
复制标题
双星相遇对银河系中心红巨星的破坏性影响
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
S. Sigurdsson
中科院分区：
文献类型：
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作者：
M. Davies;R. Blackwell;V. C. Bailey;S. Sigurdsson
我们考虑了双星和红巨星在银河系中心相遇的破坏性影响。这样的相遇可能解释了在银河系中央0.2英寸的PC内观察到的发光红巨星的枯竭。我们认为相遇涉及2-M和8-M⊙红巨星，因此跨越了对银河系中心观察到的最明亮的红巨星做出贡献的恒星质量范围。为了深入探索相遇的相空间，我们使用改进的四体代码模拟了18次X×103相遇，其中红巨核和双星的分量被视为点质量，包络构型在相遇过程中保持不变。然后，我们使用平滑粒子流体动力学(SPH)程序重新运行了少量相遇，以确认从四体运行得出的结论的可靠性。我们看到了两条通往红巨星毁灭的可能路径。很大一部分相遇导致了共同包层系统的形成，其中两个致密物体(来自红巨核和原始双星的组成部分)在共同的气态包层内形成了一个双星，而第三个天体被抛出。当双星变硬时，当信封被抛出时，红巨星的毁灭将随之而来。在较少的相遇中，侵入的双星穿过恒星，并从包层中喷出红巨核。然后，红巨型信封将在短时间尺度上消散。我们计算了这两个过程在银河中心发生的时间尺度，用于不同的双星种群。
We consider the destructive effects of encounters between binaries and red giant stars in the Galactic Centre. Such encounters may explain the observed depletion of luminous red giants within the central 0.2 pc of the galaxy. We consider encounters involving 2- and 8-M⊙ red giants, and thus span the range of stellar masses contributing to the most luminous red giants observed in the Galactic Centre. To explore the phase space of encounters thoroughly, we simulate 18 × 103 encounters using a modified four-body code in which the red giant core and components of the binary are treated as point masses, and where the envelope configuration is assumed to remain static throughout the encounter. We then rerun a small number of encounters with a smoothed particle hydrodynamics (SPH) code to confirm the reliability of conclusions drawn from the four-body runs. We see two possible pathways to red giant destruction. A large fraction of encounters lead to the formation of common-envelope systems, where two compact objects (drawn from the red giant core and the components of the original binary) form a binary within a common gaseous envelope, whilst the third body is ejected. The destruction of the red giant will then follow when the envelope is ejected as the binary hardens. In a smaller number of encounters, the intruding binary passes through the star and ejects the red giant core from the envelope. The red giant envelope will then disperse on short time-scales. We compute the time-scales for both of these processes to occur in the Galactic Centre for a variety of binary populations.