title: Sublimation in bright spots on (1) Ceres.
abstract: The dwarf planet (1) Ceres, the largest object in the main asteroid belt with a mean diameter of about 950 kilometres, is located at a mean distance from the Sun of about 2.8 astronomical units (one astronomical unit is the Earth-Sun distance). Thermal evolution models suggest that it is a differentiated body with potential geological activity. Unlike on the icy satellites of Jupiter and Saturn, where tidal forces are responsible for spewing briny water into space, no tidal forces are acting on Ceres. In the absence of such forces, most objects in the main asteroid belt are expected to be geologically inert. The recent discovery of water vapour absorption near Ceres and previous detection of bound water and OH near and on Ceres (refs 5-7) have raised interest in the possible presence of surface ice. Here we report the presence of localized bright areas on Ceres from an orbiting imager. These unusual areas are consistent with hydrated magnesium sulfates mixed with dark background material, although other compositions are possible. Of particular interest is a bright pit on the floor of crater Occator that exhibits probable sublimation of water ice, producing haze clouds inside the crater that appear and disappear with a diurnal rhythm. Slow-moving condensed-ice or dust particles may explain this haze. We conclude that Ceres must have accreted material from beyond the 'snow line', which is the distance from the Sun at which water molecules condense.
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Nathues
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Hoffmann
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schaefer
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.|Planetary Science Institute, Tucson, Arizona, USA.
authors.forename: L
authors.initials: L
authors.lastname: Le Corre
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.|Planetary Science Institute, Tucson, Arizona, USA.
authors.forename: V
authors.initials: V
authors.lastname: Reddy
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Platz
authors.affiliation: University of Winnipeg, Winnipeg, Canada.
authors.forename: E A
authors.initials: EA
authors.lastname: Cloutis
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Christensen
authors.affiliation: Freie Universitaet Berlin, Berlin, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Kneissl
authors.affiliation: Planetary Science Institute, Tucson, Arizona, USA.
authors.forename: J-Y
authors.initials: JY
authors.lastname: Li
authors.affiliation: Technische Universitaet Clausthal, Clausthal-Zellerfeld, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Mengel
authors.affiliation: Freie Universitaet Berlin, Berlin, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Schmedemann
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Schaefer
authors.affiliation: University of California, Los Angeles (UCLA), Los Angeles, California, USA.
authors.forename: C T
authors.initials: CT
authors.lastname: Russell
authors.affiliation: University of Winnipeg, Winnipeg, Canada.
authors.forename: D M
authors.initials: DM
authors.lastname: Applin
authors.affiliation: Johns Hopkins University, Laurel, Maryland, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Buczkowski
authors.affiliation: University of Winnipeg, Winnipeg, Canada.|Royal Ontario Museum, Toronto, Canada.
authors.forename: M R M
authors.initials: MR
authors.lastname: Izawa
authors.affiliation: TU Braunschweig, Braunschweig, Germany.
authors.forename: H U
authors.initials: HU
authors.lastname: Keller
authors.affiliation: Planetary Science Institute, Tucson, Arizona, USA.
authors.forename: D P
authors.initials: DP
authors.lastname: O'Brien
authors.affiliation: Brown University, Providence, Rhode Island, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Pieters
authors.affiliation: Jet Propulsion Laboratory, Pasadena, California, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Raymond
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ripken
authors.affiliation: Lunar and Planetary Institute, Houston, Texas, USA.
authors.forename: P M
authors.initials: PM
authors.lastname: Schenk
authors.affiliation: Georgia Institute of Technology, Atlanta, Georgia, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Schmidt
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Sierks
authors.affiliation: Planetary Science Institute, Tucson, Arizona, USA.
authors.forename: M V
authors.initials: MV
authors.lastname: Sykes
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: G S
authors.initials: GS
authors.lastname: Thangjam
authors.affiliation: Max Planck Institute for Solar System Research, Goettingen, Germany.
authors.forename: J-B
authors.initials: JB
authors.lastname: Vincent