TEDI的回归：重访三星中的三重演化动力学不稳定性通道
Return of the TEDI: revisiting the Triple Evolution Dynamical Instability channel in triple stars
摘要：
三星系统表现出一种被称为三重演化动力学不稳定性（TEDI）的现象，其中演化中的三重星系的质量损失引发短期动力学不稳定性，可能导致恒星碰撞，交换和喷射。先前的工作表明，TEDI是银河系中恒星迎头碰撞的重要途径，大大超过了球状星团中随机碰撞的碰撞率。在这里，我们重新审视TEDI的进化途径，使用国家的最先进的人口合成方法，自洽地考虑到恒星演化和二元相互作用，以及引力动力学和扰动通过恒星在该领域。我们发现银河系TEDI引起的碰撞率的顺序为1 e-4/年，与以前的研究是基于更简化的方法。大多数TEDI引起的碰撞涉及主序星，可能产生蓝色离散星。碰撞也有可能涉及更演化的恒星，可能产生偏心的后共包络系统，以及白矮星碰撞导致Ia型超新星（尽管后者对银河系速率的贡献可以忽略不计）。在我们的模拟中，TEDI不仅是由绝热风质量损失触发的，也是由内双星中的洛希瓣溢出触发的：当施主星的质量小于吸积星时，内双星轨道变宽，触发三重动力学不稳定性。我们发现，碰撞率增加了约17%时，飞在外地考虑。除了碰撞，我们发现TEDI产生~ 1 e-4/yr的未束缚恒星，尽管没有逃逸速度超过1 e3 km/s。
英文摘要：
Triple-star systems exhibit a phenomenon known as the Triple Evolution Dynamical Instability (TEDI), in which mass loss in evolving triples triggers short-term dynamical instabilities, potentially leading to collisions of stars, exchanges, and ejections. Previous work has shown that the TEDI is an important pathway to head-on stellar collisions in the Galaxy, significantly exceeding the rate of collisions due to random encounters in globular clusters. Here, we revisit the TEDI evolutionary pathway using state-of-the-art population synthesis methods that self-consistently take into account stellar evolution and binary interactions, as well as gravitational dynamics and perturbations from passing stars in the field. We find Galactic TEDI-induced collision rates on the order of 1e-4/yr, consistent with previous studies which were based on more simplified methods. The majority of TEDI-induced collisions involve main sequence stars, potentially producing blue straggler stars. Collisions are also possible involving more evolved stars, potentially producing eccentric post-common-envelope systems, and white dwarfs collisions leading to Type Ia supernovae (although the latter with a negligible contribution to the Galactic rate). In our simulations, the TEDI is not only triggered by adiabatic wind mass loss, but also by Roche lobe overflow in the inner binary: when the donor star becomes less massive than the accretor, the inner binary orbit widens, triggering triple dynamical instability. We find that collision rates are increased by ~17% when fly-bys in the field are taken into account. In addition to collisions, we find that the TEDI produces ~1e-4/yr of unbound stars, although none with escape speeds in excess of 1e3 km/s.
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