title: Bright carbonate deposits as evidence of aqueous alteration on (1) Ceres.
abstract: The typically dark surface of the dwarf planet Ceres is punctuated by areas of much higher albedo, most prominently in the Occator crater. These small bright areas have been tentatively interpreted as containing a large amount of hydrated magnesium sulfate, in contrast to the average surface, which is a mixture of low-albedo materials and magnesium phyllosilicates, ammoniated phyllosilicates and carbonates. Here we report high spatial and spectral resolution near-infrared observations of the bright areas in the Occator crater on Ceres. Spectra of these bright areas are consistent with a large amount of sodium carbonate, constituting the most concentrated known extraterrestrial occurrence of carbonate on kilometre-wide scales in the Solar System. The carbonates are mixed with a dark component and small amounts of phyllosilicates, as well as ammonium carbonate or ammonium chloride. Some of these compounds have also been detected in the plume of Saturn’s sixth-largest moon Enceladus. The compounds are endogenous and we propose that they are the solid residue of crystallization of brines and entrained altered solids that reached the surface from below. The heat source may have been transient (triggered by impact heating). Alternatively, internal temperatures may be above the eutectic temperature of subsurface brines, in which case fluids may exist at depth on Ceres today.
authors.forename: M C
authors.initials: MC
authors.lastname: De Sanctis
authors.forename: A
authors.initials: A
authors.lastname: Raponi
authors.forename: E
authors.initials: E
authors.lastname: Ammannito
authors.forename: M
authors.initials: M
authors.lastname: Ciarniello
authors.forename: M J
authors.initials: MJ
authors.lastname: Toplis
authors.forename: H Y
authors.initials: HY
authors.lastname: McSween
authors.forename: J C
authors.initials: JC
authors.lastname: Castillo-Rogez
authors.forename: B L
authors.initials: BL
authors.lastname: Ehlmann
authors.forename: F G
authors.initials: FG
authors.lastname: Carrozzo
authors.forename: S
authors.initials: S
authors.lastname: Marchi
authors.forename: F
authors.initials: F
authors.lastname: Tosi
authors.forename: F
authors.initials: F
authors.lastname: Zambon
authors.forename: F
authors.initials: F
authors.lastname: Capaccioni
authors.forename: M T
authors.initials: MT
authors.lastname: Capria
authors.forename: S
authors.initials: S
authors.lastname: Fonte
authors.forename: M
authors.initials: M
authors.lastname: Formisano
authors.forename: A
authors.initials: A
authors.lastname: Frigeri
authors.forename: M
authors.initials: M
authors.lastname: Giardino
authors.forename: A
authors.initials: A
authors.lastname: Longobardo
authors.forename: G
authors.initials: G
authors.lastname: Magni
authors.forename: E
authors.initials: E
authors.lastname: Palomba
authors.forename: L A
authors.initials: LA
authors.lastname: McFadden
authors.forename: C M
authors.initials: CM
authors.lastname: Pieters
authors.forename: R
authors.initials: R
authors.lastname: Jaumann
authors.forename: P
authors.initials: P
authors.lastname: Schenk
authors.forename: R
authors.initials: R
authors.lastname: Mugnuolo
authors.forename: C A
authors.initials: CA
authors.lastname: Raymond
authors.forename: C T
authors.initials: CT
authors.lastname: Russell