Dust coagulation and fragmentation in a collapsing cloud core and their influence on non-ideal magnetohydrodynamic effects
Dust coagulation and fragmentation in a collapsing cloud core and their influence on non-ideal magnetohydrodynamic effects
复制标题
塌陷云核中的灰尘凝结和破碎及其对非理想磁流体动力学效应的影响
DOI：
10.1093/mnras/stac1919
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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：
Kawasaki Yoshihiro;Koga Shunta;Machida Masahiro N
为了研究尘埃生长对非理想磁流体动力学（MHD）效应的影响，我们确定了云核坍缩过程中尘埃粒径分布的时间演化，同时考虑了尘埃凝聚和尘埃破碎。坍缩核的密度演化由一个单区模型给出。我们假设两种类型的粉尘模型：仅由硅酸盐组成的粉尘（硅酸盐粉尘）和表面被H2O冰覆盖的粉尘（H2O冰粉尘）。当只考虑碰撞混凝时，非理想MHD效应在高密度区对硅酸盐冰尘和H2O冰尘都无效。这是因为粉尘混凝降低了小粉尘颗粒的丰度，导致粉尘表面带电颗粒的吸附效率降低。在硅酸盐尘埃的情况下，当包括碰撞破碎时，由于大量的小尘埃颗粒的产生，非理想MHD效应在高密度的nh > 1012cm−3下确实适用。另一方面，对于H2O冰尘情况，由于破碎而产生的小粉尘颗粒效率不高。因此，在H2O冰尘的情况下，非理想磁流体力学效应仅适用于h≥1014cm−3的范围，即使考虑了碰撞破碎。我们的研究结果表明，要激活非理想磁流体动力学效应，必须同时考虑尘埃碰撞凝聚和破碎，而非理想磁流体动力学效应在恒星和盘的形成过程中应该发挥重要作用。
We determine the time-evolution of the dust particle size distribution during the collapse of a cloud core, accounting for both dust coagulation and dust fragmentation, to investigate the influence of dust growth on non-ideal magnetohydrodynamic (MHD) effects. The density evolution of the collapsing core is given by a one-zone model. We assume two types of dust model: dust composed only of silicate (silicate dust) and dust with a surface covered by H2O ice (H2O ice dust). When only considering collisional coagulation, the non-ideal MHD effects are not effective in the high-density region for both the silicate and H2O ice dust cases. This is because dust coagulation reduces the abundance of small dust particles, resulting in less efficient adsorption of charged particles on the dust surface. For the silicate dust case, when collisional fragmentation is included, the non-ideal MHD effects do apply at a high density ofnH> 1012cm−3because of the abundant production of small dust particles. On the other hand, for the H2O ice dust case, the production of small dust particles due to fragmentation is not efficient. Therefore, for the H2O ice dust case, non-ideal magnetohydrodynamic effects apply only in the rangenH≳ 1014cm−3, even when collisional fragmentation is considered. Our results suggest that it is necessary to consider both dust collisional coagulation and fragmentation to activate non-ideal magnetohydrodynamic effects, which should play a significant role in the star and disc formation processes.