Formation and Evolution of Binary Asteroids

Satellites of asteroids have been discovered in nearly every known small body population, and a remarkable aspect of the known satellites is the diversity of their properties. They tell a story of vast differences in formation and evolution mechanisms that act as a function of size, distance from the Sun, and the properties of their nebular environment at the beginning of Solar System history and their dynamical environment over the next 4.5 Gyr. The mere existence of these systems provides a laboratory to study numerous types of physical processes acting on asteroids and their dynamics provide a valuable probe of their physical properties otherwise possible only with spacecraft. Advances in understanding the formation and evolution of binary systems have been assisted by: 1) the growing catalog of known systems, increasing from 33 to nearly 250 between the Merline et al. (2002) Asteroids III chapter and now, 2) the detailed study and long-term monitoring of individual systems such as 1999 KW4 and 1996 FG3, 3) the discovery of new binary system morphologies and triple systems, 4) and the discovery of unbound systems that appear to be end-states of binary dynamical evolutionary paths. Specifically for small bodies (diameter smaller than 10 km), these observations and discoveries have motivated theoretical work finding that thermal forces can efficiently drive the rotational disruption of small asteroids. Long-term monitoring has allowed studies to constrain the system's dynamical evolution by the combination of tides, thermal forces and rigid body physics. The outliers and split pairs have pushed the theoretical work to explore a wide range of evolutionary end-states.Comment: 42 pages, 4 figures, contribution to the Asteroids 4 boo

Effect of rotational disruption on the size-frequency distribution of the Main Belt asteroid population

The size distribution of small asteroids in the Main Belt is assumed to be determined by an equilibrium between the creation of new bodies out of the impact debris of larger asteroids and the destruction of small asteroids by collisions with smaller projectiles. However, for a diameter less than 6 km we find that YORP-induced rotational disruption significantly contributes to the erosion even exceeding the effects of collisional fragmentation. Including this additional grinding mechanism in a collision evolution model for the asteroid belt, we generate size-frequency distributions from either an accretional (Weidenschilling, 2011) or an "Asteroids were born big" (Morbidelli, 2009) initial size-frequency distribution that are consistent with observations reported in Gladman et al. (2009). Rotational disruption is a new mechanism that must be included in all future collisional evolution models of asteroids.Comment: 5 pages, 3 figures, accepted in MNRAS letter

Marginal matters: Exploring the advancement of LGBTQ-friendly changes at a Catholic College in the United States

Extant scholarship and theory tends to overlook and mis-theorize the role that marginal actors play in organizational change and development. Therefore, this study employed and centered a multidimensional concept of marginality in an in-depth exploration of a specific organizational change and development context: a Roman Catholic College advancing LGBTQ-friendly change. An ethnographic research design employed over the course of 6 months revealed that one's marginal positionality - in relation to conditions of Invisibility, Resource Neglect, and Obedience - impacts whether and how actors advance LGBTQ-friendly change. Specifically, marginality was found to impact whether and how actors advance change through Being Out, Educating and Speaking Out, and through an approach referred to in this study as Felix Culpa. Additionally, an actors marginal positionality was found to impact 3 Levels of Connection (LoCs) to LGBTQ-friendly change at Catholic College: No Connection; an Empathetic and Galvanizing Connection; and a Structural and Intersectional Understanding (of LGBTQ-friendly change). A synthesis and theoretically sensitized interpretation of the findings revealed that - through their unique capacity to draw upon, strengthen, and nourish 'Legitimate Alternative Structural Configurations' or LASCs, marginal actors have been critical to LGBTQ-friendly change at Catholic College, and are, more broadly, instrumental in both formal and cultural change within organizations.Ph.D., Educational Leadership and Management -- Drexel University, 201