AI 中文总结
本研究通过三维全局SPH模拟发现，斯托克斯数St~0.1-1的尘埃粒子在引力不稳定盘的螺旋臂中聚集强且速度弥散低，利于尘埃驱动引力不稳定性及行星核形成。
AI 中文摘要
高分辨率ALMA观测表明，原行星盘演化的最早阶段已存在充分的行星形成过程，此时盘体通常足够巨大，受引力不稳定性（GI）调控。在该 regime 中，尘埃动力学与GI的相互作用或能促成快速核形成，但该过程的运行条件仍未得到良好约束。本研究采用三维全局SPH模拟，在宽斯托克斯数范围内探究引力不稳定盘中尘埃粒子的动力学，重点关注调控早期行星形成的三个关键量：尘埃在螺旋臂中的捕获、尘埃粒子间的碰撞速度及尘埃速度弥散。研究发现，斯托克斯数处于St~0.1-1范围内的粒子会在螺旋臂内发生最强的聚集，同时呈现低速度弥散；这种组合使该空气动力学 regime 最利于尘埃驱动的引力不稳定性启动及尘埃直接坍缩。在可直接对比碰撞速度的情况下，本三维结果与此前二维研究高度吻合，且符合粒子部分耦合于类柯尔莫哥洛夫湍流速度场的图像。研究结果表明，在年轻的自引力盘中，处于该中间耦合 regime 的尘埃粒子为行星核形成提供了自然途径。
英文摘要
High-resolution ALMA observations indicate that planet formation is already well underway in the earliest stages of disc evolution, when discs are typically massive enough to be regulated by gravitational instability (GI). In this regime, the interplay between dust dynamics and GI may enable rapid core formation, but the conditions under which this process operates remain poorly constrained. In this work, we use three-dimensional global SPH simulations to investigate the dynamics of dust particles in gravitationally unstable discs over a wide range of Stokes numbers. We focus on three key quantities that regulate early planet formation: dust trapping in spiral arms, collisional velocities between dust grains, and the dust velocity dispersion. We find that particles with Stokes numbers in the range St ~ 0.1-1 undergo the strongest concentration within spiral arms while simultaneously exhibiting low velocity dispersion. This combination makes this aerodynamic regime the most favourable for the onset of dust-driven gravitational instability and direct dust collapse. Where direct comparisons of collision velocities are possible, our three-dimensional results are in excellent agreement with previous two-dimensional studies and are consistent with a picture in which grains are partially coupled to a Kolmogorov-like turbulent velocity field in the gas. Our results indicate that, in young self-gravitating discs, dust particles in this intermediate coupling regime provide a natural pathway to the formation of planetary cores.
Comments15 pages, 9 figures, Accepted for publication on MNRAS
