Multiwavelength Characterization of the Brown Dwarf Auroral Phenomenon - Establishing the Nature of the Electrodynamic Engine

Author: Pineda, John Sebastian

Year: 2017

Degree: Dissertation (Ph.D.)

Advisor: Hallinan, Gregg W.

Committee Members: Steidel, Charles C.; Knutson, Heather A.; Kirkpatrick, J. Davy; Phinney, E. Sterl; Hallinan, Gregg W.

Option: Astronomy

DOI: 10.7907/Z90C4SRW

Abstract

Stellar coronal activity has been shown to persist into the low-mass star regime, down to late M-dwarf spectral types. However, there is now an accumulation of evidence suggesting that at the end of the main sequence there is a transition in the nature of the magnetic activity from chromospheric and coronal to planet-like and auroral, from local impulsive heating via flares and MHD wave dissipation to energy dissipation from strong large-scale magnetospheric current systems. In this dissertation, I examine the effects of these processes on the atmospheres of brown dwarfs across multiple different wavebands and investigate the underlying mechanisms powering the electrodynamic engine responsible for auroral emission in brown dwarfs. I conduct observational surveys looking for the emission features of Hα and H3+ as indicative of auroral systems across the ultracool dwarf regime. I further provide a comprehensive view of brown dwarf magnetic activity and auroral phenomena, detailing the various emission processes, and expectations for auroral brown dwarfs. I also initiate a preliminary analysis of the detailed emission features and discuss the constraints imposed on the electrodynamic engine of these objects.

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