Most asteroids originated in larger parent bodies that underwent accretion and heating during the first few million years of the solar system. We investigated the parent body of S-type asteroid 25143 Itokawa by developing a computational model which can approximate the thermal evolution of an early solar system body. We compared known constraints on Itokawa’s thermal history to simulations of its parent body and constrained its time of formation to between 1.6 and 2.5 million years after the beginning of the solar system, though certain details could allow for even earlier or later formation. These results stress the importance of precise data required of the material properties of asteroids and meteorites to place better constraints on the histories of their parent bodies. Additional mathematical and computational details are discussed, and the full code and data is made available online.

This creative project develops an environment in which three species inhabit a shared land and models the movement of the creatures to determine the survival rates over time in specific conditions. The three species modelled include a predator and a prey species with movement capabilities as well as a stagnant fruit species. There are a variety of configurable variables that can be used to modify and control the simulation to observe how the resulting population charts change. The big difference between this project and a normal approach to simulating a predation relationship is that actual creatures themselves are being created and their movement is simulated in this virtual environment which then leads to population counts, rather than integrating differential equations relating the population sizes of both species and purely tracking the populations but not the creatures themselves. Because of this difference, my simulation is not meant to handle all the complexities of life that come in the real-world but instead is intended as a simplified approach to simulating creatures' lives with the purpose of conveying the idea of a real predation relationship. Thus, the main objective of my simulation is to produce data representative of real-world predator-prey relationships, with the overall cyclical pattern that is observed in natural achieved through simulating creature movement and life itself rather than estimating population size change.

As the search for life in our universe grows, it is important to not only locate planets outside of our solar system, but also to work towards the ability to understand and characterize their nature. Many current research endeavors focus on the discovery of exoplanets throughout the surrounding universe; however, we still know very little about the characteristics of these exoplanets themselves, particularly their atmospheres. Observatories, such as the Hubble Space Telescope and the Spitzer Space Telescope, have made some of the first observations which revealed information about the atmospheres of exoplanets but have yet to acquire complete and detailed characterizations of exoplanet atmospheres. The EXoplanet Climate Infrared TElescope (EXCITE) is a mission specifically designed to target key information about the atmospheres of exoplanets - including the global and spatially resolved energy budget, chemical bulk-compositions, vertical temperature profiles and circulation patterns across the surface, energy distribution efficiency as a function of equilibrium temperatures, and cloud formation and distribution - in order to generate dynamic and detailed atmospheric characterizations. EXCITE will use phase-resolved transit spectroscopy in the 1-4 micron wavelength range to accomplish these science goals, so it is important that the EXCITE spectrograph system is designed and tested to meet these observational requirements. For my thesis, I present my research on the EXCITE mission science goals and the design of the EXCITE spectrograph system to meet these goals, along with the work I have done in the beginning stages of testing the EXCITE spectrograph system in the lab. The primary result of my research work is the preparation of a simple optics setup in the lab to prepare a laser light source for use in the EXCITE spectrograph system - comparable to the preparation of incoming light by the EXCITE telescope system - which successfully yields an F# = 12.9 and a spot size of s = 39 ± 7 microns. These results meet the expectations of the system and convey appropriate preparation of a light source to begin the assembly and testing of the EXCITE spectrograph optics in the lab.

The goal of this project was to develop a prototype for an educational tool that will help users understand how the voting system deployed by a government can affect the outcomes of elections. This tool was developed in Java SE, consisting of a model for the simulation of elections capable of supporting various voting systems, along with a variety of fairness measures, and educational and explanatory material. While a completed version of this tool would ideally be fully self-contained, easily accessible in-browser, and provide detailed visualizations of the simulated elections, the current prototype version consists of a GitHub repository containing the code, with the educational material and explanations contained within the thesis paper. Ultimately, the goal of this project was to be a stepping stone on the path to create a tool that will instill a measure of systemic skepticism in the user; to give them cause to question why our systems are built the way they are, and reasons to believe that they could be changed for the better. In undertaking this project, I hope to help in providing people with the political education needed to make informed decisions about how they want the government to function. The GitHub repository containing all the code can be found at, https://github.com/SpencerDiamond/Votes_that_Count

We implemented the well-known Ising model in one dimension as a computer program and simulated its behavior with four algorithms: (i) the seminal Metropolis algorithm; (ii) the microcanonical algorithm described by Creutz in 1983; (iii) a variation on Creutz’s time-reversible algorithm allowing for bonds between spins to change dynamically; and (iv) a combination of the latter two algorithms in a manner reflecting the different timescales on which these two processes occur (“freezing” the bonds in place for part of the simulation). All variations on Creutz’s algorithm were symmetrical in time, and thus reversible. The first three algorithms all favored low-energy states of the spin lattice and generated the Boltzmann energy distribution after reaching thermal equilibrium, as expected, while the last algorithm broke from the Boltzmann distribution while the bonds were “frozen.” The interpretation of this result as a net increase to the system’s total entropy is consistent with the second law of thermodynamics, which leads to the relationship between maximum entropy and the Boltzmann distribution.

Debris disks are a collection of dust grains and planetesimals around a star and are thought to contain the remnants of planet formation. Directly imaging debris disks and studying their morphologies is valuable for studying the planet formation process. In some stellar systems that have a directly imaged debris disk, there are also directly imaged planets. Debris disk structures like gaps and asymmetries can show the gravitational e↵ects of planets that are below the brightness threshold for being detected via direct imaging. We investigate a sample of debris disks in Scorpius-Centaurus (Sco-Cen) that were imaged with the Gemini Planet Imager (GPI), which is an adaptive optics system with a coronagraph to block starlight. We look at two GPI data sets, the GPIES campaign Sco-Cen targets, and a follow-up observing program for Sco-Cen targets. We resolve 5 debris disks in the follow-up program and 13 from the GPIES campaign. By calculating contrast curves, we determine the planet detection limit in each of the GPI images. We find that we could have detected 5 Jupiter mass planets at angular separations greater than about 0.6 arcseconds in our GPIES campaign images. In three of our images we could have detected 2 Jupiter mass planets in wide orbits, but 2 Jupiter masses below the detection limit in our other images. We identify one point source around HD 108904 as a sub-stellar companion candidate. To further check for evidence of planets that are below the detection limit, we measure the surface brightness profile of the disks to check for asymmetries in brightness. We find that one of the edge-on disks has an asymmetric surface brightness profile, HD 106906, and three other edge-on disks have symmetric surface brightness profiles. We also find that two disks, HD 106906 and HD 111520, are asymmetric in radial extent, which is possibly evidence for gravitational interactions with planets.