Aaron DeLeon (left) with his advisor, Dr. Tracy Becker (right), following the successful defense of his dissertation, Advancing Asteroid Characterization: Novel Techniques Applied to Characterizing Binary Near-Earth Asteroids and Thermal Modeling of Vesta.
Congratulations to Aaron Deleon on successfully passing his dissertation!
His dissertation, “Advancing Asteroid Characterization: Novel Techniques Applied to Characterizing Binary Near-Earth Asteroids and Thermal Modeling of Vesta,” explores innovative methods for studying asteroids using radar, optical lightcurve, and infrared observations. His work advances our understanding of near-Earth asteroids, planetary science, and planetary defense while also improving techniques used to characterize asteroid systems and evaluate thermal models.
Dissertation Abstract
Aaron De Leon
“Advancing Asteroid Characterization: Novel Techniques Applied to Characterizing Binary Near-Earth Asteroids and Thermal Modeling of Vesta”
Asteroids contain important clues to fundamental theories regarding the solar system, life on Earth, and now planetary defense. Therefore, characterizing the physical properties of asteroids is key to advancing planetary science and enabling successful mitigation strategies for planetary defense. Radar and mid-infrared observations are crucial tools for these exact endeavors.
We discuss the physical characterization of two near-Earth binary asteroids, (163693) Atira and (285263) 1998 QE2, using optical lightcurve observations and radar observations from the Arecibo Observatory. We produce shape models for each system’s components, as well as a complex shape model of the 1998 QE2 satellite. We also derive physical and spin-state characteristics for each component including size, spin-axis orientation, rotation period, and crucially, density. We use the mutual orbit of the system along with the shape-derived volume to calculate the density and use mutual events detected in lightcurve observations to confirm the spin-axis orientation and the mutual orbit solution. We also employ a new orbit solving algorithm within the asteroid shape modeling software used for this work.
We also discuss using calibrator target data from the airborne Stratospheric Observatory For Infrared Astronomy (SOFIA) as a long baseline thermal study of (4) Vesta. We use aperture photometry to obtain photometric spectra for several flights over six years of observations which is then used to model the spectral energy distribution of Vesta. With the modeled thermal emission of Vesta, we model the beaming parameter, η, in an effort to understand the thermal evolution of Vesta over the six year observation span. We also attempt to obtain emissivity of Vesta using the modeled thermal emission and spectral observations from SOFIA. Overall, a trend of an increase in η plus lower spectral flux over time lead to speculation on instrument degradation of the Faint Object infraRed CAmera for the SOFIA Telescope (FORCAST).
Altogether, we provide implications for infrared studies that used the FORCAST instrument aboard SOFIA with future work aimed at quantifying any instrument degradation. And, we have contributed two of the nine asteroid densities determined in the last 14 years (with one of three techniques which obtain low uncertainty values) and demonstrated the technique of using mutual events for characterizing near-Earth asteroids which can be applied to dozens of radar observed binary systems.