A new binary formation mechanism
A new binary formation mechanism
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一种新的二元形成机制
DOI：
10.1093/mnras/269.3.837
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发表时间：
1994
影响因子：
4.8
通讯作者：
I. Bonnell
中科院分区：
文献类型：
--
作者：
I. Bonnell
本文提出了一种通过原恒星盘碎裂形成双星系统的新机制。这个过程需要一个强烈的旋转不稳定（bothm= 2 andm= 1模式），中央吸积对象所包围的旋转支撑盘的气体，这是受持续下降。中心不稳定性由于它们= 1模的增长而偏离中心。旋臂的相互作用，使旋臂进入盘状结构，并继续下沉，在第一个旋臂周围的轨道上形成一个自引力的第二个旋臂。对于没有盘状结构的核，核的演化与过去的旋转不稳定性研究一样。除了它们= 2 bar模式，anm= 1模式发展，允许原恒星将其部分自旋角动量转换为轨道角动量。此外，来自棒的重力力矩直接解释了角动量的向外传递。对于由周围圆盘形成并持续下降的核心，来自核心的螺旋臂穿过圆盘将物质聚集在一起。它们的组合= 2模式和核心从它们的位移= 1模式允许螺旋臂从盘和持续的下落中收集足够的物质，使其变得重力不稳定。然后这个物质坍缩形成次级物质。在没有持续下落到圆盘上的情况下，旋臂（从它们= 1和m = 2模式）不能收集足够的材料来形成金斯不稳定凝聚。
A new mechanism for the formation of binary systems through the fragmentation of a protostellar disc is presented. This process requires a strongly rotationally unstable (to bothm= 2 andm= 1 modes), central accreting object surrounded by a rotationally supported disc of gas which is subject to continuing infall. The central instability becomes off-centre due to the growth of them= 1 mode. The interaction of the spiral arms thus driven into the disc, with the continued infall, gives rise to the formation of a self-gravitating secondary body in orbit around the first.For cores that form without discs, the core evolves as in past studies of rotational instabilities. In addition to them= 2 bar mode, anm= 1 mode develops, allowing the protostar to convert some of its spin angular momentum into orbital angular momentum. Furthermore, the gravitational torques from the bar directly account for the outward transfer of angular momentum.For cores that form with surrounding discs and with continuing infall, the spiral arms from the core move through the disc gathering matter together. The combination of them= 2 mode and the displacement of the core from them= 1 mode allows the spiral arms to gather sufficient matter together from the disc and the continuing infall to become gravitationally unstable. This matter then collapses to form a secondary. In cases where there is no continuing infall on to the disc, the spiral arms (from them= 1 andm= 2 modes) are not able to gather sufficient material to form a Jeans unstable condensation.