Thermophysical modeling of NEOWISE observations of DESTINY+ targets Phaethon and 2005 UD (1907.04518v1)

Abstract: Thermophysical models allow for improved constraints on the physical and thermal surface properties of asteroids beyond what can be inferred from more simple thermal modeling, provided a sufficient number of observations is available. We present thermophysical modeling results of observations from the NEOWISE mission for two near-Earth asteroids which are the targets of the DESTINY+ flyby mission: (3200) Phaethon and (155140) 2005 UD. Our model assumes a rotating, cratered, spherical surface, and employs a Monte Carlo Markov Chain to explore the multi-dimensional parameter space of the fit. We find an effective spherical diameter for Phaethon of $4.6^{+0.2}_{-0.3}~$km, a geometric albedo of $p_V=0.16\pm0.02$, and a thermal inertia $\Gamma=880$ $^{+580}_{-330}$, using five epochs of NEOWISE observations. The best model fit for (155140) 2005 UD was less well constrained due to only having two NEOWISE observation epochs, giving a diameter of $1.2\pm0.4~$km and a geometric albedo of $p_V=0.14\pm0.09$.