The origin of (90) Antiope double binary asteroid remains an unsolved puzzle, despite an intensive campaign of observations conducted mostly using the VLT-UT4 telescope equipped with an adaptive Optics system (NACO) in 2007 (Descamps et al., Icarus 2007) and lightcurve data analysis by Descamps et al (Icarus, in press, 2009). These studies suggested that the two rubble pile (density ∼1.3 g/cc porosity∼50%) ellipsoidal (D∼86 km) components have similar surface characteristics and that a 68-km bowl-shaped impact crater is located on one of the components. This giant crater could be the aftermath of a tremendous collision of a 100-km sized proto-Antiope with another Themis family member. This violent shock could have produced the break-up of proto-Antiope into two equisized bodies.To test if the components come from the same parent body, we recorded individual spectra of the components using SPIFFI, a near-infrared (1.1 - 2.45 μm) integral field spectrograph fed by SINFONI, an adaptive optics module available on VLT-UT4. Using our orbital model we requested telescope time when the separation of the components of 90 Antiope was larger than 0.087” during the Feb. 2009 opposition to minimize the contamination between components. Their spectra, in J band (R-2000, S/N=70) and H+K band (R=1500, S/N=230) were recorded in Feb 01.25, Feb 03.30 and Feb 21.20 UT. The data reduction is still in progress. We could extract the H+K spectra on two epochs (Feb 01 and 21). The spectra of each component do not display any significant absorption features and their slope is in aggrement with typical C-type near-infrared spectra from De Meo et al (Icarus, 2009). They are quite similar, with typical variations by less than 5%, and imply that both bodies were formed at the same time from the same material. We acknowledge the support from NSF grant AAG-0807468.
AAS/Division for Planetary Sciences Meeting Abstracts #41
- Pub Date:
- September 2009