Nathues, Andreas and Mottola, Stefano and Kaasalainen, Mikko and Neukum, Gerhard (2005) Color Variations of 15 Eunomia. IAU Symposium 229, Asteroids, Comets, Meteors, 2005-08-07 - 2005-08-12, Buzios, Brasilien.
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We present color ratio curves of the S-asteroid 15 Eunomia, which have been extracted from high-precision photometric lightcurves obtained in three different VNIR wavelength bands at the Bochum Telescope, La Silla. The measured color ratio curves and near infrared spectra were used to derive a detailed surface composition model whose shape has been computed by V-lightcurve inversions. According to this analysis, the asteroid shows on one hemisphere a higher concentration of pyroxene, which causes an increased 440/700 nm and a reduced 940/700 nm reflectance ratio as well as a pronounced 2-ìm absorption band. The remaining surface shows a higher concentration of olivine, leading to a reduced 440/700 nm and slightly increased 940/700 nm color ratio. In addition, we found that the maximum of the 440/700 nm color ratio curve coincides with the minimum of the 940/700 nm color ratio curve and vice versa. We demonstrate on the basis of USGS laboratory spectra that this anti-cyclical behavior can be explained by choosing Fe-rich olivine and a pyroxene with moderate Fe content as varying mineral phases. Furthermore, our observations confirm that 15 Eunomia is an irregular elongated and at least partially differentiated body. In addition, partial differentiation is supported by spectral observations of several fragments, which show differences in the olivine to pyroxene abundance ratio (Nathues 2000, ISSN 1434-8454).
|Document Type:||Conference or Workshop Item (Poster)|
|Title:||Color Variations of 15 Eunomia|
|Date:||7 August 2005|
|In ISI Web of Science:||No|
|Keywords:||Asteroids, Asteroid composition, Asteroid surfaces, Spectrophotometry, Spectroscopy|
|Event Title:||IAU Symposium 229, Asteroids, Comets, Meteors|
|Event Location:||Buzios, Brasilien|
|Event Type:||international Conference|
|Event Dates:||2005-08-07 - 2005-08-12|
|HGF - Research field:||Aeronautics, Space and Transport (old)|
|HGF - Program:||Space (old)|
|HGF - Program Themes:||W EW - Erforschung des Weltraums|
|DLR - Research area:||Space|
|DLR - Program:||W EW - Erforschung des Weltraums|
|DLR - Research theme (Project):||W - Vorhaben Asteroiden und Kometen (old)|
|Institutes and Institutions:||Institute of Planetary Research > Asteroids and Comets|
|Deposited By:||Dr.phys. Stefano Mottola|
|Deposited On:||11 Apr 2006|
|Last Modified:||27 Apr 2009 04:57|
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