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| Titel |
Comparison of ground-based and VIRTIS-M/ROSETTA reflectance spectra of asteroid 2867 Šteins with laboratory reflectance spectra in the VIS and IR |
| VerfasserIn |
Kathrin Markus, Gabriele Arnold, Harald Hiesinger, Fabrizio Capaccioni, Gianrico Filacchione, Federico Tosi, Maria Cristina De Sanctis, Maria Teresa Capria, Eleonora Ammannito, Stephane Erard |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082280
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| Zusammenfassung |
| Asteroid 2867 Šteins was encountered by Rosetta on September 5, 2008. During
this close encounter the VIRTIS spectrometer aboard Rosetta acquired spectra of
Šteins in the wavelength range from 0.2 μm to 5 μm [1]. We compare ground-based
VIS and NIR reflectance spectra of Šteins [2, 3, 4, 5, 6, 7] with the reflectance
spectra obtained by OSIRIS [8] and VIRTIS-M during the fly-by and laboratory
reflectance spectra of enstatite achondrites (aubrites) and minerals (enstatite, oldhamite,
albite).
Ground-based and fly-by observations show an overall flat spectrum with the typical
E[II]-type absorptions bands at 0.49 μm and ~0.9 μm. E-type asteroids have been
associated to aubrites in view of their large reflectance and overall featureless spectrum.
Compared to the ground-based observations the VIRTIS spectrum shows an additional
absorption feature at 0.6 μm. The lack of absorption bands at 1 μm and 2 μm indicates
that Šteins’ surface has no Fe-bearing pyroxenes or olivines. At wavelengths 1 μm are flat and featureless. At wavelengths >2.5 μm, only covered by
VIRTIS, the spectrum is also flat and featureless, except for wavelengths >3.5 μm that
are affected by thermal emission which contributes significantly to the detected
radiation.
Our laboratory reflectance spectra of aubrites fit the overall characteristics of the Šteins
spectrum, but are unable to reproduce the prominent 0.49 μm absorption band. The amount of
oldhamite, showing a band at 0.49 μm and thus considered as a possible component of the
surface material [9], needed to reproduce the 0.49 μm absorption band in ground-based
spectra [3, 6] is >40% and is not consistent with the composition of aubrites. Oldhamite is
only an accessory phase with abundances usually |
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