Dust motion and possibility of dust growth in a growing circumstellar disk
Dust motion and possibility of dust growth in a growing circumstellar disk
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尘埃运动和不断增长的星周盘中尘埃生长的可能性
DOI：
10.1093/mnras/stac3503
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发表时间：
2022
影响因子：
4.8
通讯作者：
Machida Masahiro N
中科院分区：
文献类型：
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作者：
Koga Shunta;Machida Masahiro N
为了研究恒星形成早期的尘埃运动，我们用三维磁流体模拟计算了恒星形成云核的演化，将尘埃颗粒视为拉格朗日粒子。我们制备了六组不同大小的尘埃颗粒，其范围为0.01-m，其中是尘埃颗粒的大小。在引力塌缩的星云中，环绕原恒星的星盘形成，并驱动原恒星外流。几乎所有初始分布在≲0≲45°区域的小尘埃粒子(adθ10-m)都被外流从中心抛出，这里的Ad 0是相对于旋转轴的初始天顶角，而分布在该区域的大尘埃粒子(M)只有一小部分被抛出。所有其他颗粒落在原恒星或圆盘上，没有被流出的物质抛出。无论尘埃颗粒的大小如何，尘埃粒子进入星周盘后，尘埃运动的行为分为两种趋势。从上包层到达内盘区的尘埃粒子优先落到原恒星上，而从包层到达外盘区或盘外缘的尘埃粒子可以在没有向内径向漂移的情况下存活下来。这些幸存下来的颗粒可能会导致尘埃生长。因此，我们预计外盘区域可能是行星形成的有利地点。
We calculate the evolution of a star-forming cloud core using a three-dimensional resistive magnetohydrodynamics simulation, treating dust grains as Lagrangian particles, to investigate the dust motion in the early star formation stage. We prepare six different-sized set of dust particles in the rangead= 0.01–m, whereadis the dust grain size. In a gravitationally collapsing cloud, a circumstellar disk forms around a protostar and drives a protostellar outflow. Almost all the small dust grains (ad≲ 10–m) initially distributed in the region θ0≲ 45° are ejected from the center by the outflow, where θ0is the initial zenith angle relative to the rotation axis, whereas only a small number of the large dust grains (m) distributed in the region are ejected. All other grains fall onto either the protostar or disk without being ejected by the outflow. Regardless of the dust grain size, the behavior of the dust motion is divided into two trends after dust particles settle into the circumstellar disk. The dust grains reaching the inner disk region from the upper envelope preferentially fall onto the protostar, while those reaching the outer disk region or disk outer edge from the envelope can survive without an inward radial drift. These surviving grains can induce dust growth. Thus, we expect that the outer disk regions could be a favored place of planet formation.