标题： 恒星形成早期阶段吸积爆发的起源 显示英文标题

标题： The Origin of Episodic Accretion Bursts in the Early Stages of Star Formation

摘要： 我们通过数值模拟研究了旋转云核的演化，从磁超临界核的坍缩到原恒星的形成，以及主要吸积阶段中原恒星盘的发展。 我们发现，盘很快变得不稳定，并发展出类似于最近在AB Aurigae观测到的螺旋结构。 来自原恒星包层的连续物质坠落使原恒星盘变得不稳定，导致螺旋臂的形成以及它们内部致密原恒星/原行星团块的形成。 螺旋臂强度的增长和随之而来的质量和角动量重新分布，在盘中产生了强烈的离心不平衡，并触发了质量吸积爆发，在此期间，致密的原恒星/原行星团块落入中心的原恒星。 这些团块坠落的事件可能表现为FU奥里变量中观察到的剧烈吸积率（\ge 10^{-4} M_sun/yr）的事件。 在这些吸积爆发之间，原恒星表现出较低的吸积率（< 10^{-6} M_sun/yr）。 在间歇性吸积阶段，原恒星盘的质量小于或相当于原恒星的质量。 显示英文摘要

摘要： We study numerically the evolution of rotating cloud cores, from the collapse of a magnetically supercritical core to the formation of a protostar and the development of a protostellar disk during the main accretion phase. We find that the disk quickly becomes unstable to the development of a spiral structure similar to that observed recently in AB Aurigae. A continuous infall of matter from the protostellar envelope makes the protostellar disk unstable, leading to spiral arms and the formation of dense protostellar/protoplanetary clumps within them. The growing strength of spiral arms and ensuing redistribution of mass and angular momentum creates a strong centrifugal disbalance in the disk and triggers bursts of mass accretion during which the dense protostellar/protoplanetary clumps fall onto the central protostar. These episodes of clump infall may manifest themselves as episodes of vigorous accretion rate (\ge 10^{-4} M_sun/yr) as is observed in FU Orionis variables. Between these accretion bursts, the protostar is characterized by a low accretion rate (< 10^{-6} M_sun/yr). During the phase of episodic accretion, the mass of the protostellar disk remains less than or comparable to the mass of the protostar.