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# Program information file
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PROGRAM_ID           2023A027
PROGRAM_TITLE        The characterisation of the potentially differentiated Kalliope asteroid family.
PROGRAM_INV1         Chrysa Avdellidou
PROGRAM_INV2         Marco Delbo
PROGRAM_INV3         Kevin Walsh
PROGRAM_INV4         Pierre Vernazza
PROGRAM_INV5         Michael Marsset
PROGRAM_SCICAT       main-belt / Trojan asteroids
PROGRAM_ABSTRACT_BEG
In the classical theory of planetesimal differentiation, a body would form an iron-rich core, an olivine-dominated mantle, and a pyroxene-rich basaltic crust. The detection of differentiated bodies in the current asteroid main belt will allow to get insights and study the very initial phases of planetesimal accretion. So far, the only proof of a differentiated planetesimal is the case of asteroid [4] Vesta and its family, which are linked with the howardite--eucrite--diogenite meteorites that correspond to the crust of a differentiated planetesimal. Spectroscopic searches for other differentiated material have proven successful. However, this material is spread throughout the belt with no connection to each other. The asteroid family of Kalliope belongs to C/X-complex and its members have geometric visible albedos spanning a wide range [0.1-0.35]. Moreover, [22] Kalliope appears to be the densest known solar system small body, supporting the argument for a metallic interior and thus a differentiated body. If the original planetesimal from which Kalliope originates accreted beyond the snow line and contains as much carbon measured in the carbonaceous chondrite meteorites, then the high internal temperatures would lead to the production of materials such as enstatite or other iron-poor pyroxene, metallic iron, and possibly silica. We request IRTF observing time to spectroscopically characterise the largest members of the Kalliope family. In this framework, Kalliope family would be the second discovered differentiated family after Vesta, and the only differentiated family that is potentially linked to carbonaceous-chondrite-related iron meteorites. Near-infrared spectra are required to measure the spectral slope and distinguish the C from the X-complex asteroids and identify [or not] the presence of the 0.9--1 um absorption feature that distinguishes the X-complex classes. The IRTF observations will be combined with the Gaia visible spectra.
PROGRAM_ABSTRACT_END