Lucy Trojan Targets in the Mid-Infrared: JWST MIRI-MRS Observations
Session 1.04 Spectroscopy
Monday 06-24 | 10:10 - 10:30

Jupiter Trojan asteroids, located at Jupiter's L4 and L5 Lagrange points, constitute a dynamically stable small body population crucial for understanding Solar System formation. These primitive asteroids tie together formation theories and dynamical models that explain how our Solar System formed. Trojans share important characteristics with the dynamically excited Kuiper Belt populations and the Neptune Trojans as they are hypothesized to have been sourced from the same region. As such, Trojans may be one of the most accessible examples of the planetesimals that populated the outer protoplanetary disk. Spectral analysis of fourteen Trojans in the Mid-Infrared (MIR; 5–35 μm) reveals regoliths dominated by fine-particulate amorphous and crystalline silicates, aligning with outer Solar System formation theories. However, their low albedos and almost featureless near-infrared (NIR; 0.7 – 2.5 μm) spectra pose mysteries, especially given the scarcity of MIR observations compared to NIR. NASA's Lucy mission marks the first in situ exploration of Trojan asteroids. Over the next decade, Lucy will conduct flybys of five Trojan systems: (3548) Eurybates, (15094) Polymele, (11351) Leucus, (21900) Orus, and (617) Patroclus. Using the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) in Medium Resolution spectroscopy (MRS) mode as part of the Cycle 1 GO program (ID 2574) we observed Lucy's Trojan targets. MIRI MRS observations cover the ~5 – 27.9 μm spectral range. We will present our silicate mineralogy analysis and compare compositions with other dynamically linked small body populations. We will additionally show comparisons of JWST spectra of Eurybates and Patroclus with existing MIR spectra from the Spitzer Space Telescope.

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