论文标题
分子云的辐射磁脉冲模拟中的大量prestell核心
Massive Prestellar Cores in Radiation-magneto-turbulent Simulations of Molecular Clouds
论文作者
论文摘要
我们使用基于网格的代码RAMSES-RT模拟了在一组巨型分子云（GMC）的辐射磁通型 - 流动力模拟中，以少量分辨率模拟Prestellar核心的形成和崩溃。鉴于我们的最佳知识，我们首次通过缩放GMC内的个体庞大的Prestellar内核来采用现实的初始/边界条件。我们确定了两种不同的破碎方式：“准球形”和“丝状”。在这两种模式中，片段最终都嵌入了带有半径〜500-5000 au的准稳态积聚磁盘或环形磁盘中，开口角$ h/r \ sim 0.5-1 $。磁盘/环形曲线是稳定的，但发现促进的片段被发现绕外磁盘绕，看起来是磁盘碎片。每个核心将近100％的气体质量转换为磁盘中心附近形成的几个巨大恒星。高质量恒星周围的大而巨大的磁盘受外部磁盘中的磁压力支撑，在半径> 200-1000 au处，内部磁盘中的湍流压力。最大的核心积聚比其初始质量高出几倍，形成了一个（原始的）恒星簇，由四颗巨大的恒星组成，被环状颗粒笼罩着，这表明对超高质量恒星形成的竞争积聚场景。我们还发现，单个巨星产生的HII区域仍被困在密集的杂质磁盘中几百公斤，而大型二进制文件或多个系统中巨大恒星的动态运动可将恒星从磁盘最密集的部分移动，从而使紫外线辐射避免产生稳定或脉动稳定或脉动的Bipolsal bipolar hii区域。
We simulate the formation and collapse of prestellar cores at few-AU resolution in a set of radiation-magneto-hydrodynamic simulations of giant molecular clouds (GMCs) using the grid-based code RAMSES-RT. We adopt, for the first time to our best knowledge, realistic initial/boundary conditions by zooming-in onto individual massive prestellar cores within the GMC. We identify two distinct modes of fragmentation: "quasi-spherical" and "filamentary". In both modes the fragments eventually become embedded in a quasi-steady accretion disk or toroid with radii ~ 500-5000 AU and opening angles $H/R \sim 0.5-1$. The disks/toroids are Toomre stable but the accreted pre-existing fragments are found orbiting the outer disk, appearing as disk fragmentation. Each core converts nearly 100 percent of the gas mass into a few massive stars forming near the disk center. Large and massive disks around high-mass stars are supported by magnetic pressure in the outer disk, at radii >200-1000 AU, and turbulent pressure in the inner disk. The most massive core accretes several times more mass than its initial mass, forming a (proto)star cluster of 8 massive stars enshrouded by a toroid, suggesting a competitive accretion scenario for ultra-high-mass star formation. We also find that the HII regions produced by a single massive star remain trapped in the dense circumstellar disks for a few hundred kiloyears, while the dynamic motions of massive stars in wide binaries or multiple systems displace the stars from the densest parts of the disk, allowing UV radiation to escape producing steady or pulsating bipolar HII regions.
