标题： 从中心塌缩到年轻恒星周围的转动：原行星盘的起源 显示英文标题

标题： From Infall to Rotation around Young Stars: The Origin of Protoplanetary Disks

摘要： 围绕年轻恒星的盘状结构起源直接关系到我们对行星系统形成过程的理解。 在恒星形成的星际云中，角动量由磁场调节，防止收缩核心加速旋转。当约0.03 pc大小的致密核心从磁场中解耦并动态坍缩时，约10^-3 km/s·pc的比角动量被锁定在系统中。粘性吸积盘是重新分配角动量的两种可能机制之一；另一种机制是多星系统的形成。 本文回顾了最近涉及高角分辨率观测的研究结果：嵌套在坍缩包层深处的盘状结构；包围盘状结构的吸积激波；缓慢旋转包层中的坍缩速度场；一个可能的过渡天体，其特征为大尺寸且正在收缩的盘状结构；以及金牛T型恒星周围的盘状结构中的速度场。 在未来几年内即将出现的观测设施有望在研究原行星盘起源方面取得显著进展。 显示英文摘要

摘要： The origin of disks surrounding young stars has direct implications for our understanding of the formation of planetary systems. In the interstellar clouds from which star form, angular momentum is regulated by magnetic fields, preventing the spin up of contracting cores. When ~0.03 pc-sized dense cores decouple from the magnetic field and collapse dynamically, ~10^-3 km/s*pc of specific angular momentum is locked into the system. A viscous accretion disk is one of two possible mechanisms available for the necessary redistribution of angular momentum; the other one is the formation of a multiple stellar system. Recent observational results involving high-angular resolution observations are reviewed: the presence of disks deep inside collapsing envelopes; an accretion shock surrounding a disk; the velocity field in collapsing and slowly rotating envelopes; a possible transitional object, characterized as a large, contracting disk; and the velocity field in disks around T Tauri stars. Observational facilities becoming available over the next several years promise to offer significant progress in the study of the origin of protoplanetary disks.