The Origin and Properties of Magnetic Dynamos Across the Sub-Stellar Boundary

这个项目是一个系统的研究，从无线电到x射线波长，在超冷矮星的磁性发电机的起源和性质。这些是低质量、未进化的恒星和亚恒星物体，它们弥合了恒星与行星之间的差距，在数量上主宰了银河系的恒星群。超冷矮星具有完全对流的内部，长期以来一直被认为是磁性不活跃的。然而，最近对这些天体的研究发现了意想不到的强烈磁活动。利用扩展甚大阵列的灵敏度和带宽的提高，对60000个斯隆数字巡天超冷矮星的时间分辨光谱的新实施，以及对磁等离子体加热和粒子加速的同时观测，该项目将解决基本的开放性问题：(i)磁场强度的分布；（ii）磁场的尺度、几何形状和相干时间尺度；(3)发电机机构效率与旋转、年龄、二值性等特性之间是否存在相关性。本科生和研究生将获得获取、分析和发布电磁波谱数据的经验，以及低质量恒星、褐矮星、系外行星和恒星磁场领域的专业知识。该项目还将把这些经验整合到本科教育中，并通过学生积极参与哈佛-史密森尼望远镜的观测，缩小课堂学习和实践研究之间的差距。

This project is a systematic study, from radio to X-ray wavelengths, of the origin and properties of magnetic dynamos in ultracool dwarf stars. These are low-mass, unevolved stars and sub-stellar objects that bridge the star-planet gap and dominate the Galactic stellar population by number. Ultracool dwarfs have fully convective interiors and were long assumed to be magnetically inactive. However, recent studies of these objects uncovered unexpectedly vigorous magnetic activity. Taking advantage of the increase in sensitivity and bandwidth of the Expanded Very Large Array, a new implementation of time-resolved spectroscopy for 60,000 Sloan Digital Sky Survey ultracool dwarfs, and simultaneous observations of magnetic plasma heating and particle acceleration, the project will address fundamental open questions: (i) the distribution of magnetic field strengths; (ii) the scale, geometry, and coherence timescale of the magnetic fields; and (iii) whether there is a correlation between the dynamo mechanism efficiency and properties such as rotation, age, or binarity. Undergraduate and graduate students will gain experience with the acquisition, analysis, and publication of data across the electromagnetic spectrum, as well as expertise in the areas of low mass stars, brown dwarfs, extrasolar planets, and stellar magnetic fields. The project will also integrate this experience into undergraduate education, and narrow the gap between classroom learning and hands-on research, through the active participation of students in observing with Harvard-Smithsonian telescopes.