Chevance Mélanie, Kruijssen J M Diederik, Vazquez-Semadeni Enrique, Nakamura Fumitaka, Klessen Ralf, Ballesteros-Paredes Javier, Inutsuka Shu-Ichiro, Adamo Angela, Hennebelle Patrick
1Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstraße 12-14, 69120 Heidelberg, Germany.
2Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de Méxíco, Campus Morelia, Apdo. Postal 3-72, Morelia, 58089 Mexico.
Space Sci Rev. 2020;216(4):50. doi: 10.1007/s11214-020-00674-x. Epub 2020 Apr 28.
Giant molecular clouds (GMCs) and their stellar offspring are the building blocks of galaxies. The physical characteristics of GMCs and their evolution are tightly connected to galaxy evolution. The macroscopic properties of the interstellar medium propagate into the properties of GMCs condensing out of it, with correlations between e.g. the galactic and GMC scale gas pressures, surface densities and volume densities. That way, the galactic environment sets the initial conditions for star formation within GMCs. After the onset of massive star formation, stellar feedback from e.g. photoionisation, stellar winds, and supernovae eventually contributes to dispersing the parent cloud, depositing energy, momentum and metals into the surrounding medium, thereby changing the properties of galaxies. This cycling of matter between gas and stars, governed by star formation and feedback, is therefore a major driver of galaxy evolution. Much of the recent debate has focused on the durations of the various evolutionary phases that constitute this cycle in galaxies, and what these can teach us about the physical mechanisms driving the cycle. We review results from observational, theoretical, and numerical work to build a dynamical picture of the evolutionary lifecycle of GMC evolution, star formation, and feedback in galaxies.
巨分子云（GMCs）及其恒星后代是星系的基石。巨分子云的物理特性及其演化与星系演化紧密相连。星际介质的宏观性质会传递到从中凝聚出的巨分子云的性质中，例如星系和巨分子云尺度的气体压力、表面密度和体积密度之间存在相关性。通过这种方式，星系环境为巨分子云内的恒星形成设定了初始条件。在大质量恒星形成开始后，诸如光致电离、恒星风以及超新星爆发等恒星反馈最终会促使母云消散，将能量、动量和金属物质沉积到周围介质中，从而改变星系的性质。因此，由恒星形成和反馈所控制的气体与恒星之间的物质循环是星系演化的主要驱动力。近期的诸多争论聚焦于构成星系中这个循环的各个演化阶段的持续时间，以及这些阶段能让我们了解到哪些驱动该循环的物理机制。我们回顾了观测、理论和数值研究的结果，以构建一幅关于星系中巨分子云演化、恒星形成和反馈的演化生命周期的动力学图景。
