Ammoniated phyllosilicates with a likely outer Solar System origin on (1) Ceres
Journal
Date Issued
2015
Author(s)
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Ammannito, E.
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Marchi, S.
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McCord, T. B.
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McSween, H. Y.
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Giardino, M.
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Magni, G.
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Combe, J. -P.
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Feldman, W.
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Jaumann, R.
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McFadden, L. A.
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Pieters, C. M.
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Prettyman, T.
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Toplis, M.
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Raymond, C. A.
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Russell, C. T.
Description
We thank the following institutions and agencies, which supported this work: the Italian Space Agency (ASI), the National Aeronautic and Space Administration (NASA, USA) and the Deutsches Zentrum fr Luft- und Raumfahrt (DLR, Germany). The VIR was funded and coordinated by the Italian Space Agency and built by SELEX ES, with the scientific leadership of the Institute for Space Astrophysics and Planetology, Italian National Institute for Astrophysics, Italy, and is operated by the Institute for Space Astrophysics and Planetology, Rome, Italy. A portion of this work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. We thank J. L. Bishop and D. Takir for reviews, and D. Takir for providing spectra of carbonaceous chondrites plotted in Fig. 2 .
Abstract
Studies of the dwarf planet (1) Ceres using ground-based and orbiting telescopes have concluded that its closest meteoritic analogues are the volatile-rich CI and CM carbonaceous chondrites. Water in clay minerals, ammoniated phyllosilicates, or a mixture of Mg(OH)2 (brucite), Mg2CO3 and iron-rich serpentine have all been proposed to exist on the surface. In particular, brucite has been suggested from analysis of the mid-infrared spectrum of Ceres. But the lack of spectral data across telluric absorption bands in the wavelength region 2.5 to 2.9 micrometres—where the OH stretching vibration and the H2O bending overtone are found—has precluded definitive identifications. In addition, water vapour around Ceres has recently been reported, possibly originating from localized sources. Here we report spectra of Ceres from 0.4 to 5 micrometres acquired at distances from ~82,000 to 4,300 kilometres from the surface. Our measurements indicate widespread ammoniated phyllosilicates across the surface, but no detectable water ice. Ammonia, accreted either as organic matter or as ice, may have reacted with phyllosilicates on Ceres during differentiation. This suggests that material from the outer Solar System was incorporated into Ceres, either during its formation at great heliocentric distance or by incorporation of material transported into the main asteroid belt.
Volume
528
Issue
7581
Start page
241
Issn Identifier
0028-0836
Ads BibCode
2015Natur.528..241D
Rights
open.access
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