Cosmic ray ionization rate versus dust fraction: Which plays a crucial role in the early evolution of the circumstellar disc?
Cosmic ray ionization rate versus dust fraction: Which plays a crucial role in the early evolution of the circumstellar disc?
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宇宙射线电离率与尘埃分数：哪个在星周盘的早期演化中起着至关重要的作用？
DOI：
10.1093/mnras/stad711
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发表时间：
2023
影响因子：
4.8
通讯作者：
Tsukamoto Yusuke
中科院分区：
文献类型：
--
作者：
Kobayashi Yudai;Takaishi Daisuke;Tsukamoto Yusuke
利用三维非理想磁流体动力学（MHD）模拟方法研究了年轻恒星天体（YSO）的形成和早期演化，探讨了宇宙线电离率和尘埃含量（或尘埃颗粒数量）对星周盘形成的影响.我们的模拟结果表明，较高的宇宙射线电离率和较低的尘埃分数导致（i）较小的磁电阻率的双极扩散，（ii）较小的磁盘大小和质量，（iii）较早的流出形成的时间和较大的角动量的流出。特别是在高宇宙射线电离率下，模拟早期形成的圆盘在大约104年的时间尺度上被磁制动分散。我们的研究结果表明，宇宙射线电离率对盘的形成和演化有特别大的影响，而尘埃分数的影响并不显著。
We study the formation and early evolution of young stellar objects (YSOs) using three-dimensional non-ideal magnetohydrodynamic (MHD) simulations to investigate the effect of cosmic ray ionization rate and dust fraction (or amount of dust grains) on circumstellar disc formation. Our simulations show that a higher cosmic ray ionization rate and a lower dust fraction lead to (i) a smaller magnetic resistivity of ambipolar diffusion, (ii) a smaller disc size and mass, and (iii) an earlier timing of outflow formation and a greater angular momentum of the outflow. In particular, at a high cosmic ray ionization rate, the discs formed early in the simulation are dispersed by magnetic braking on a time-scale of about 104yr. Our results suggest that the cosmic ray ionization rate has particularly a large impact on the formation and evolution of discs, while the impact of the dust fraction is not significant.