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  • Asteroid 16 Psyche: Shape, ...
    Shepard, Michael K.; de Kleer, Katherine; Cambioni, Saverio; Taylor, Patrick A.; Virkki, Anne K.; Rívera-Valentin, Edgard G.; Rodriguez Sanchez-Vahamonde, Carolina; Fernanda Zambrano-Marin, Luisa; Magri, Christopher; Dunham, David; Moore, John; Camarca, Maria

    The planetary science journal, 08/2021, Letnik: 2, Številka: 4
    Journal Article

    Abstract We develop a shape model of asteroid 16 Psyche using observations acquired in a wide range of wavelengths: Arecibo S -band delay-Doppler imaging, Atacama Large Millimeter Array (ALMA) plane-of-sky imaging, adaptive optics (AO) images from Keck and the Very Large Telescope (VLT), and a recent stellar occultation. Our shape model has dimensions 278 (−4/+8 km) × 238(−4/+6 km) × 171 km (−1/+5 km), an effective spherical diameter D eff = 222-1/+4 km, and a spin axis (ecliptic lon, lat) of (36°, −8°) ± 2°. We survey all the features previously reported to exist, tentatively identify several new features, and produce a global map of Psyche. Using 30 calibrated radar echoes, we find Psyche’s overall radar albedo to be 0.34 ± 0.08 suggesting that the upper meter of regolith has a significant metal (i.e., Fe–Ni) content. We find four regions of enhanced or complex radar albedo, one of which correlates well with a previously identified feature on Psyche, and all of which appear to correlate with patches of relatively high optical albedo. Based on these findings, we cannot rule out a model of Psyche as a remnant core, but our preferred interpretation is that Psyche is a differentiated world with a regolith composition analogous to enstatite or CH/CB chondrites and peppered with localized regions of high metal concentrations. The most credible formation mechanism for these regions is ferrovolcanism as proposed by Johnson et al. (2020).