The Hidden Lives of Massive Protostars: Fragmentation, Disks, and Feedback

虽然在开发低质量恒星的恒星形成过程的标准模型方面已经取得了相当大的进展，但我们距离理解大质量恒星是如何形成的还有很长的路要走。大质量恒星产生宇宙中的大多数金属，通过它们的电离辐射、风和超新星主导星际和星际介质的能量平衡，并通过它们与附近的原行星盘相互作用来塑造行星的形成。如果没有一个可靠的大质量恒星形成模型，就不可能理解这些过程。在这个项目中，Mark Kruholz博士(加州大学圣克鲁斯分校)将利用分析研究和包括重力、辐射和磁流体力学在内的高分辨率模拟的补充工具来开发这样一个模型。作为研究的一部分，必须解决一些问题和问题。在大质量恒星形成的最早阶段，我们必须了解碎裂过程。是什么物理机制控制了气体碎片的大小到不到一个太阳质量，还是整体坍塌成一颗大质量的恒星？一旦崩塌开始，任何模型都必须描述如何克服吸积的两个主要障碍，角动量和辐射压力。圆盘是一种可能的解决方案，因为它们重新分配角动量，同时它们的高不透明度保护气体免受辐射。这个项目的第二个重要部分是发展对大质量原恒星盘的理解。在大质量恒星形成过程的末尾，是什么最终停止了吸积并清除了所有剩余的气体？除了致力于这些问题，并使用与这项研究相关的材料，克鲁姆霍尔茨博士还将在克鲁姆霍尔茨博士十年监狱教育经验的基础上，为加利福尼亚州圣克鲁斯附近监狱的囚犯提供数学和科学课程。克鲁姆霍尔茨博士将邀请加州大学圣克鲁斯分校的教职员工和学生参与这项活动，从而促进科学界与服务严重不足、主要是少数族裔的人群之间的互动。

While there has been considerable progress toward the development of a standard model for the process of star formation in the case of low mass stars, we are much further from understanding how massive stars form. Massive stars produce most of the metals in the universe, dominate the energy balance of both the interstellar and intergalactic media via their ionizing radiation, winds, and supernovae, and shape the formation of planets through their interactions with nearby protoplanetary disks. No understanding of these processes is possible without a reliable model of massive star formation. In this project, Dr. Mark Krumholz (University of California - Santa Cruz) will develop such a model, using the complementary tools of analytic investigation and high resolution simulation including gravity, radiation, and magnetohydrodynamics.As part of this research a number of questions and problems must be addressed. At the earliest stages of massive star formation, we must understand the fragmentation process. What physical mechanisms control whether gas fragments down to sizes less than one solar mass or collapses monolithically to a massive star? Once collapse begins, any model must describe how to overcome the two dominant barriers to accretion, angular momentum and radiation pressure. Disks are a likely solution, since they redistribute angular momentum while at the same time their high opacity shields gas from radiation. A second important part of this project is to develop an understanding of massive protostellar disks. At the end of the massive star formation process, what eventually halts accretion and clears away any remaining gas? In addition to working on these questions, and using material related to this research, Dr. Krumholtz will also offer math and science courses to prison inmates in prisons near Santa Cruz, California, building on Dr. Krumholz's decade of experience in prison education. Dr. Krumholtz will involve faculty, staff, and students at UC Santa Cruz in this activity, thereby facilitating interactions between the scientific community and a radically under-served, largely minority population.