0 Assigned ID: 1526 ----- Attempting Submission 1 (Wed Apr 07 04:28:35 GMT 2021) ----- High-resolution HST images of debris disks have revealed startling morphologies reflective of processes endemic to the pre-main-sequence, post-planet-formation era. HD 61005 and HD 32297 sport dramatically swept-back ansae likened to "Moth'' wings; HD 15115 hosts a lopsided ''Needle''; and AU Mic features a twisting firehose spraying dust at super-escape speeds. We will investigate how these diverse and still unexplained phenomena may stem from the same kind of underlying event: the catastrophic collisional disruption of a single potentially Vesta-class body. The collision site marks a ''cascade point'' where debris from the destroyed body continues to grind against the parent background disk, generating dust which if bound should occupy apsidally aligned orbits - this is the key geometric condition needed to explain Moths and Needles. In AU Mic, the cascade point provides the firehose spout from which emerges a stream of unbound dust accelerated radially and vertically by a powerful and cyclical magnetized stellar wind. We will develop the theory of how catastrophic collisions unfold in disks and synthesize new scattered-light images to compare with the HST observations. Under a unified and coherent framework, we seek to explain the perennially mysterious east-west asymmetry in HD 61005, the parallel arc in HD 32297, and the fastest moving clouds and their vertical displacements in AU Mic, as well as constrain the properties of disrupted bodies and predict disk colors for future observations. Dr. Eugene Chiang is a theorist with extensive experience modeling debris disks and the dynamics of collisional cascades. Dr. Chiang has led 5 theoretical studies of debris disks with his students and postdocs (on Fomalhaut, AU Mic, HD 61005, HD 32297, HD 15115, and others), and has co-authored a number of papers on debris disks led by observers using HST, Keck, and Gemini data. These observers include Drs. Gaspard Duchene, Paul Kalas, and Thomas Esposito who have expertise in analyzing optical/infrared scattered-light and thermal-emission data on debris disks. Dr. Eve Lee is the author of the scattered-light radiative transfer code that will be used to generate synthetic images to compare against the HST images. Dr. Jeffrey Fung is the author of the dust avalanche code used to model the dust streams emanating from the cascade point in the AU Mic debris disk. Exoplanets and Exoplanet Formation 0 Regular false false false true false SUPPORTED