Field stars are frequently formed in pairs, and many of these binaries are part of triples or even higher-order systems. Even though, the principles of single stellar evolution and binary evolution, have been accepted for a long time, the long-term evolution of stellar triples is poorly understood. The presence of a third star in an orbit around a binary system can significantly alter the evolution of those stars and the binary system. The rich dynamical behaviour in three-body systems can give rise to Lidov-Kozai cycles, in which the eccentricity of the inner orbit and the inclination between the inner and outer orbit vary periodically. In turn, this can lead to an enhancement of tidal effects (tidal friction), gravitational-wave emission and stellar interactions such as mass transfer and collisions. The lack of a self-consistent treatment of triple evolution, including both three-body dynamics as well as stellar evolution, hinders the systematic study and general understanding of the long-term evolution of triple systems. In this paper, we aim to address some of these hiatus, by discussing the dominant physical processes of hierarchical triple evolution, and presenting heuristic recipes for these processes. To improve our understanding on hierarchical stellar triples, these descriptions are implemented in a public source code TrES, which combines three-body dynamics (based on the secular approach) with stellar evolution and their mutual influences. Note that modelling through a phase of stable mass transfer in an eccentric orbit is currently not implemented in TrES, but can be implemented with the appropriate methodology at a later stage.

中文翻译：

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等级三重星系的演变

野外恒星通常成对形成，其中许多双星是三重甚至更高阶系统的一部分。即使单星演化和二元进化的原理已经被接受很长时间了，但对星三元组的长期演化却知之甚少。围绕双星系统的轨道中存在第三颗恒星会极大地改变这些恒星和双星系统的演化。三体系统中丰富的动力学行为会引起Lidov-Kozai循环，其中内轨道的偏心率和内外轨道之间的倾斜度会定期变化。反过来，这会导致潮汐效应（潮汐摩擦），引力波发射和恒星相互作用（例如传质和碰撞）增强。缺乏包括三体动力学和恒星演化在内的三重进化的自洽处理，阻碍了对三重系统的长期演化的系统研究和普遍理解。在本文中，我们旨在通过讨论分层三级进化的主要物理过程，并为这些过程提供启发式方法，以解决其中的一些问题。为了增进对分层恒星三元组的理解，这些描述在公共源代码TrES中实现，该代码结合了三体动力学（基于长期方法）与恒星演化及其相互影响。请注意，目前在TrES中尚未实现通过偏心轨道中稳定的质量传递阶段进行建模的方法，但是可以在以后的阶段中使用适当的方法来实现。