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Identification of spectral units on Phoebe |
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| Authors: | A. Coradini F. Tosi F. Capaccioni G. Filacchione R.H. Brown V. Formisano J.I. Lunine K.H. Baines B.J. Buratti D.P. Cruikshank P. Drossart Y. Langevin T.B. McCord R.M. Nelson B. Sicardy M.M. Hedman C.A. Hibbitts C. Griffith |
| Affiliation: | a INAF-IFSI, Istituto di Fisica dello Spazio Interplanetario, Area Ricerca Tor Vergata, Via Fosso del Cavaliere 100, I-00133 Roma, Italy b INAF-IASF, Istituto di Astrofisica Spaziale e Fisica Cosmica, Area Ricerca Tor Vergata, Via Fosso del Cavaliere 100, I-00133 Roma, Italy c South-Russian State Technical University, Prosveschenia 132, Novocherkassk 346428, Russia d Lunar and Planetary Laboratory and Steward Observatory, 1629 University Boulevard, University of Arizona, Tucson, AZ 85721, USA e INAF-OACT, Osservatorio Astrofisico di Catania, Via S. Sofia 78, I-95123 Catania, Italy f Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA g Institut d'Astrophysique Spatiale, Université de Paris-Sud, Bâtiment 121, F-91405 Orsay, France h US Geological Survey, Mail Stop 964, Box 25046, Denver Federal Center, Denver, CO 80225, USA i NASA Ames Research Center, Moffett Field, CA 94035-1000, USA j Observatoire de Paris-Meudon, 5 place Jules Janssen, F-92190 Meudon, France k Institute for Planetary Exploration, German Aerospace Center (DLR), Rutherfordstrasse 2, D-12489 Berlin, Germany l Department of Earth and Space Sciences, University of Washington, 310 Condon Hall, Box 351310, Seattle, WA 98195-1310, USA m INAF-OAC, Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli, Italy n Cornell University, 418 Space Sciences Building, Ithaca, NY 14853, USA o Laboratoire de Planétologie et Géodynamique, Université de Nantes, 2 rue de la Houssinière, B.P. 92208, F-44322 Nantes Cedex 3, France p Planetary Sciences Institute NW, 225 S. Lake Avenue, Suite 300, Pasadena, CA 91101, USA |
| Abstract: | We apply a multivariate statistical method to the Phoebe spectra collected by the VIMS experiment onboard the Cassini spacecraft during the flyby of June 2004. The G-mode clustering method, which permits identification of the most important features in a spectrum, is used on a small subset of data, characterized by medium and high spatial resolution, to perform a raw spectral classification of the surface of Phoebe. The combination of statistics and comparative analysis of the different areas using both the VIMS and ISS data is explored in order to highlight possible correlations with the surface geology. In general, the results by Clark et al. [Clark, R.N., Brown, R.H., Jaumann, R., Cruikshank, D.P., Nelson, R.M., Buratti, B.J., McCord, T.B., Lunine, J., Hoefen, T., Curchin, J.M., Hansen, G., Hibbitts, K., Matz, K.-D., Baines, K.H., Bellucci, G., Bibring, J.-P., Capaccioni, F., Cerroni, P., Coradini, A., Formisano, V., Langevin, Y., Matson, D.L., Mennella, V., Nicholson, P.D., Sicardy, B., Sotin, C., 2005. Nature 435, 66-69] are confirmed; but we also identify new signatures not reported before, such as the aliphatic CH stretch at 3.53 μm and the ∼4.4 μm feature possibly related to cyanide compounds. On the basis of the band strengths computed for several absorption features and for the homogeneous spectral types isolated by the G-mode, a strong correlation of CO2 and aromatic hydrocarbons with exposed water ice, where the uniform layer covering Phoebe has been removed, is established. On the other hand, an anti-correlation of cyanide compounds with CO2 is suggested at a medium resolution scale. |
| Keywords: | Saturn, satellites Satellites, composition Irregular satellites Spectroscopy |
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