[en] Dwarf-planet (1) Ceres is one of the two targets, along with (4) Vesta, that will be studied by the NASA Dawn spacecraft via imaging, visible and near-infrared spectroscopy, and gamma-ray and neutron spectroscopy. While Ceres' visible and near-infrared disk-integrated spectra have been well characterized, little has been done about quantifying spectral variations over the surface. Any spectral variation would give us insights on the geographical variation of the composition and/or the surface age. The only work so far was that of Rivkin and Volquardsen ([2010], Icarus 206, 327) who reported rotationally-resolved spectroscopic (disk-integrated) observations in the 2.2-4.0 μm range; their observations showed evidence for a relatively uniform surface.Here, we report disk-resolved observations of Ceres with SINFONI (ESO VLT) in the 1.17-1.32 μm and 1.45-2.35 μm wavelength ranges. The observations were made under excellent seeing conditions (0.6″), allowing us to reach a spatial resolution of ˜75 km on Ceres' surface. We do not find any spectral variation above a 3% level, suggesting a homogeneous surface at our spatial resolution. Slight variations (about 2%) of the spectral slope are detected, geographically correlated with the albedo markings reported from the analysis of the HST and Keck disk-resolved images of Ceres (Li et al. [2006], Icarus 182, 143; Carry et al. [2008], Astron. Astrophys. 478, 235). Given the lack of constraints on the surface composition of Ceres, however, we cannot assert the causes of these variations.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Carry, Benoît; European Space Astronomy Centre, ESA, P.O. Box 78, 28691 Villanueva de la Cañada, Madrid, Spain ; LESIA, Observatoire de Paris Meudon - CNRS, 5 place Jules Janssen, 92195 Meudon Cedex, France
Vernazza, Pierre; European Southern Observatory, K. Schwarzschild-Str. 2, 85748 Garching, Germany ; Laboratoire dAstrophysique de Marseille, 38 rue Frédéric Joliot-Curie, 13388 Marseille, France
Dumas, Christophe; European Southern Observatory, Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago de Chile, Chile
Merline, William J; Southwest Research Institute, 1050 Walnut St. # 300, Boulder, CO 80302, USA
Mousis, Olivier; Université de Franche Comté - CNRS, Institut UTINAM, 41 bis av. de l'Observatoire, F-25010 Besançon Cedex, France
Rousselot, Philippe; Université de Franche Comté - CNRS, Institut UTINAM, 41 bis av. de l'Observatoire, F-25010 Besançon Cedex, France
Jehin, Emmanuel ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Astrophysique et traitement de l'image
Manfroid, Jean ; Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Fulchignoni, Marcello; LESIA, Observatoire de Paris Meudon - CNRS, 5 place Jules Janssen, 92195 Meudon Cedex, France
Zucconi, Jean*-Marc; Université de Franche Comté - CNRS, Institut UTINAM, 41 bis av. de l'Observatoire, F-25010 Besançon Cedex, France ; Deceased.
Language :
English
Title :
The remarkable surface homogeneity of the Dawn mission target (1) Ceres
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