A Combination of Hydrated and Dehydrated Silicates on the S Asteroid 11 Parthenope?
V. V. Busarev (SSAI, Moscow University)
Reflectance spectra of 11 Parthenope in the range with
a spectral resolution of have been obtained near it's oppositi-
on in September 1993 in the course of a night using solar-type refe-
rence star (HD11170). It has been done with a scanning spectrophotome-
ter mounted on the 1.25 m telescope in Crimea. The spectra show some
weak absorption features which may be ascribed to layer silicates.
General shape of the spectra agrees with classification of Parthenope as
S asteroid. Nevertheless, there are unusual weak absorption bands at
(up to in depth), (up to ), and mo-
re faint (ab. ) ones at 0.47, 0.59, 0.63, 0.68, and . It is interesting that the absorption features at 0.38 and
are like in parameters to those found by us on the M aste-
roid 201 Penelope. Resembling absorption bands were registered also
on the S asteroid 181 Eucharis (Vilas et al. 1993, Icarus 102,
225-231). The spectral features of Parthenope in the reflectance spec-
tra are in a correspondence with a pattern of absorptions in spectrum of
terrestrial chlorite (A. N. Platonov 1973. The nature of mineral colo-
ring. - Kiev, Naukova Dumka Press, 98).
The presence of absorption bands at 0.51 and ( )
attributed to pyroxenes (Burns et al. 1972, Proc. Lunar Sci. Conf.
3rd, 533-543) in the obtained spectra of the asteroid together with
features mentioned above allows to suppose that combinations of layer
silicates and unaltered igneous minerals are possible on 11 Parthe-
nope and some other S and M asteroids.