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

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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.