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

该项目从无线电到X射线波长，对超冷矮星中磁发电机的起源和性质进行系统研究。 这些都是低质量的，未进化的恒星和亚恒星物体，它们填补了恒星-行星之间的空白，并在数量上主导了银河系的恒星种群。超冷矮星内部完全对流，长期以来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场活动。利用扩展甚大阵列灵敏度和带宽的提高，这是对60，000个斯隆数字巡天超冷矮星进行时间分辨光谱学的一种新的实施方式，并同时观测磁等离子体加热和粒子加速，该项目将解决基本的未决问题：（ii）磁场的尺度、几何形状和相干时间尺度;以及（iii）发电机机制效率与诸如旋转、年龄或二元性之类的属性之间是否存在相关性。本科生和研究生将获得在整个电磁频谱数据的采集，分析和出版的经验，以及在低质量恒星，褐矮星，太阳系外行星和恒星磁场领域的专业知识。该项目还将把这一经验融入本科教育，并通过学生积极参与哈佛-史密森望远镜的观测，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.