Asteroid 16 Psyche: Shape, Features, and Global Map
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 Deff = 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).
- Publication:
-
The Planetary Science Journal
- Pub Date:
- August 2021
- DOI:
- 10.3847/PSJ/abfdba
- arXiv:
- arXiv:2110.03635
- Bibcode:
- 2021PSJ.....2..125S
- Keywords:
-
- Main belt asteroids;
- Asteroids;
- Asteroid surfaces;
- Radar telescopes;
- Radar astronomy;
- 2036;
- 72;
- 2209;
- 1330;
- 1329;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 45 pages, 10 embedded figures, 6 tables