A Portrait of the Sun as a Young Star: Studying Space Weather Around Young Suns in the Optical and Radio

The surface and atmospheric chemistry of solar system bodies---including the Earth---are heavily influenced by transient particle events from the Sun like coronal mass ejections (CMEs) and solar energetic particles (SEP). These events, alongside the electromagnetic (EM) radiation of solar flares, comprise what we call space weather. The energy of both the EM and particle events are expected to have been orders of magnitude higher when the Sun was much younger, which raises questions with regards to the evolution of angular momentum, chemistry, and habitability throughout our solar system's history. Studying this history requires we study young stars as proxies for the young Sun, but the particle environment of other stars is notoriously difficult to study and CMEs or SEPs are even more so due to their transience and the multi-wavelength nature of their signatures. Fully characterizing an event thus requires extensive, coordinated monitoring across many instruments. To address this requirement for studying space weather, I present the beginning of the Space Weather Around Young Suns (SWAYS) program in this thesis. This program includes the Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA) for identifying stellar analogs of solar type II and III bursts which are associated with bulk plasma motion from the Sun. The SWAYS program also includes Flarescope which I designed and built to detect photometric signatures of flares from solar-type stars with high precision at optical wavelengths. With Flarescope and the OVRO-LWA, I have collected more than 800 hours of simultaneous data on six young, solar-type stars and have developed a framework for analyzing the results of their coordination. This thesis includes a technical overview of Flarescope’s design, a summary of its performance with the OVRO-LWA, and the framework for using the two instruments to search for signatures of transient particle flux. I supplement the significance of simultaneous observations of solar-type stars at optical and radio wavelengths with my work with the Very Large Array Sky Survey and Transiting Exoplanet Survey Satellite data. In this work, I identify unprecedented stellar radio emission and develop the relationship between such emission and stellar superflares. In all, this thesis illustrates the significance of simultaneous radio and optical observations for constraining stellar space weather and highlights the feasibility of multi-wavelength monitoring.