论文标题
建模磁盘和磁性流出围绕形成巨大的恒星：I。研究积聚磁盘的两个层结构
Modeling disks and magnetic outflows around a forming massive star: I. Investigating the two layer-structure of the accretion disk
论文作者
论文摘要
就像他们的较低的群众兄弟姐妹一样，可以预期大量的原恒星：a）被偶尔磁盘包围，b）发射磁性驱动的喷气机和流出。因此，磁盘的形成和全局演变由大尺度的角动量，磁制动的效率和介质的电阻率以及磁盘的内部热和磁压力控制。我们通过由最初均匀的磁场螺纹的重力塌陷进行了一系列30个模拟，该恒星由云的不同值，其初始密度和旋转曲线，其旋转能量含量，磁场强度和材料的电阻性。气体和灰尘以电阻性磁流失动力学的方法进行建模，还考虑了热发射和自我实力的辐射运输。在重力塌陷中占主导地位的初始输入相后，形成了积聚磁盘，不久后推出了磁驱动的流出。可以在积聚磁盘中区分两层：一个薄层，垂直由热压支撑，厚层由磁压垂直支撑。在我们的基金情况下，我们观察到磁盘内部〜50 au的磁制动的影响。参数研究表明，磁盘的大小主要取决于初始质量储量的密度和旋转曲线，而不是磁场强度。磁压可以稍微增加积聚磁盘的大小，而磁制动在磁盘的最内部更相关，而不是外磁盘。从参数研究中，我们可以推断出重力塌陷发作的多个初始条件能够产生给定的磁盘尺寸和原恒星质量。
Like their lower mass siblings, massive protostars can be expected to: a) be surrounded by circumstellar disks and b) launch magnetically-driven jets and outflows. The disk formation and global evolution is thereby controlled by advection of angular momentum from large scales, the efficiency of magnetic braking and the resistivity of the medium, and the internal thermal and magnetic pressures of the disk. We perform a series of 30 simulations of a massive star forming from the gravitational collapse of a molecular cloud threaded by an initially-uniform magnetic field, starting from different values for the mass of the cloud, its initial density and rotation profiles, its rotational energy content, the magnetic field strength, and the resistivity of the material. The gas and dust is modeled with the methods of resistive magnetohydrodynamics, also considering radiation transport of thermal emission and self-gravity. After the initial infall phase dominated by the gravitational collapse, an accretion disk is formed, shortly followed by the launching of magnetically-driven outflows. Two layers can be distinguished in the accretion disk: a thin layer, vertically supported by thermal pressure, and a thick layer, vertically supported by magnetic pressure. We observe the effects of magnetic braking in the inner ~50 au of the disk at late times in our fiducial case. The parameter study reveals that the size of the disk is mostly determined by the density and rotation profiles of the initial mass reservoir and not by the magnetic field strength. Magnetic pressure can slightly increase the size of the accretion disk, while magnetic braking is more relevant in the innermost parts of the disk as opposed to the outer disk. From the parameter study, we infer that multiple initial conditions for the onset of gravitational collapse are able to produce a given disk size and protostellar mass.
