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Compositional differences among Bright Spots on the Ceres surface

Palomba, E. and Longobardo, A. and De Sanctis, M. C. and Stein, N. T. and Ehlmann, B. and Galiano, A. and Raponi, A. and Ciarniello, M. and Ammannito, E. and Cloutis, E. and Carrozzo, F. G. and Capria, M. T. and Stephan, K. and Zambon, F. and Tosi, F. and Raymond, C. A. and Russell, C. T. (2019) Compositional differences among Bright Spots on the Ceres surface. Icarus, 320 . pp. 202-212. ISSN 0019-1035. http://resolver.caltech.edu/CaltechAUTHORS:20170921-091013749

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Abstract

At the beginning of the Ceres investigation, the Dawn-NASA mission discovered a large bright spot (BS) in the Occator crater floor. Several other smaller bright spots were discovered during the following phases of the mission. In this paper, a complete survey for the detection of BS on the Ceres surface have been made by using the hyperspectral data acquired by Visible and Infrared Mapping Spectrometer (VIR). The hyperspectral images span the spectral range from 0.2 to 5 µm, by using two channel, the VIS channel with a spectral sampling of 1.8 nm and a IR channel with a spectral sampling of 9.8 nm. Finally a catalogue of 92 BS has been compiled and their compositional properties have been examined. In particular, five spectral parameters have been applied to perform the analysis: the photometrically corrected reflectance and four band depths, related to spectral absorptions at 2.7 µm (OH fundamental indicative of phyllosilicates), at 3.05 µm (due to ammoniated clays), at 3.4 and 4.0 µm (carbonate overtones). The 90% of BS are impact-related features (ejecta, crater rim, crater floor, crater wall). The two brightest BS, Cerealia and Vinalia Faculae, are located on the Occator crater floor. Most of BSs show features similar to the average Ceres surface, which has low reflectance and is composed of Mg-phyllosilicates and ammoniated clays, with a reduced abundance of MgCa carbonates. Cerealia and Vinalia Faculae are a peculiar BS family, with a high abundance of Na-carbonates and Al-rich phyllosilicates. Oxo and a companion bright spot represents a third category, depleted in phyllosilicates and with a high to moderate albedo. Carbonate composition ranges from Mg/Ca to Na components. Haulani, Ernutet, Kupalo, and other two BS's represent another group, with intermediate properties between the typical BS and the Oxo family: they are moderately rich in carbonates and slightly depleted in Mg- and ammoniated phyllosilicates. The four families probably explain a single evolutionary path followed by the BS from the formation to their maturity: initially the very fresh bright spots would possess characteristics similar to Cerealia and Vinalia Faculae; with time, salts and OH volatilize and a light mixing with surrounding material would produce Oxo-like BS's; additional strong mixing would form Haulani-like BS, which finally become a typical bright spots.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1016/j.icarus.2017.09.020DOIArticle
ORCID:
AuthorORCID
Ehlmann, B.0000-0002-2745-3240
Additional Information:© 2017 Elsevier Inc. Received 26 April 2017, Revised 8 September 2017, Accepted 18 September 2017, Available online 20 September 2017. VIR is funded by the Italian Space Agency–ASI and was developed under the leadership of INAF-Istituto di Astrofisica e Planetologia Spaziali, Rome-Italy. The instrument was built by Selex-Galileo, Florence-Italy. The authors acknowledge the support of the Dawn Science, Instrument, and Operations Teams. This work was supported by ASI and NASA.
Funders:
Funding AgencyGrant Number
Agenzia Spaziale Italiana (ASI)UNSPECIFIED
NASAUNSPECIFIED
Record Number:CaltechAUTHORS:20170921-091013749
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20170921-091013749
Official Citation:E. Palomba, A. Longobardo, M.C. De Sanctis, N.T. Stein, B. Ehlmann, A. Galiano, A. Raponi, M. Ciarniello, E. Ammannito, E. Cloutis, F.G. Carrozzo, M.T. Capria, K. Stephan, F. Zambon, F. Tosi, C.A. Raymond, C.T. Russell, Compositional differences among Bright Spots on the Ceres surface, Icarus, Volume 320, 2019, Pages 202-212, ISSN 0019-1035, https://doi.org/10.1016/j.icarus.2017.09.020. (http://www.sciencedirect.com/science/article/pii/S0019103517303135)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81665
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:21 Sep 2017 18:20
Last Modified:22 Mar 2019 21:48

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