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Astron. Astrophys. 327, 388-391 (1997)

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4. Discussion and conclusion

A better investigation of the spectra obtained and a consequent clearer classification of the objects here presented would require near-infrared data. In fact, this could allow a more detailed comparison with the spectra of OC and also a comparison with the S-subclasses as designed by Gaffey et al. (1993). Nevertheless, the results obtained are suggestive of some conclusions.

Among the eight observed objects, only one, 1864 Daedalus, had been previously classified as an SQ-type and we confirm the belonging to the S class. All the others show the typical trend of S-type objects, except 2063 Bacchus which spectrum has the typical behaviour of C-type objects. Four of the observed objects (1864 Daedalus, 5836 1993 MF, 3352 McAuliffe and 5876 Talos) show a spectrum that, within the errors, match quite consistently the laboratory spectra of OC. So these objects are potential parent bodies for these meteorites and this could suggest: a main-belt origin and a surface formed by undifferentiated mineral assemblages. The differences between the four objects similar to the OC and the other three typical S type asteroids could be due to space weathering effects: different ages of the objects are probably responsible of different surface reflectance characteristics (Chapman, 1996). The asteroids which composition is closer to OC would be those with "younger" surfaces (Binzel et al. 1996).

The asteroid 5836 1993 MF, besides its similarity to OC assemblages, shows also an absorption band centered around 6000 Å suggestive of the presence of aqueous altered materials.

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© European Southern Observatory (ESO) 1997

Online publication: April 8, 1998