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Catalogue POP – Notice individuelle de publication

Vernazza Pierre, Castillo-Rogez Julie C., Beck P., Emery Joshua P., Brunetto Rosario, Delbo Marco, Marsset Michael, Marchis Franck, Groussin Olivier, Zanda Brigitte, Lamy Philippe, Jorda Laurent, Mousis Olivier, Delsanti Audrey, Djouadi Zahia, Dionnet Z., Borondics F., Carry Benoît

Different Origins or Different Evolutions? Decoding the Spectral Diversity Among C-type Asteroids

The Astronomical Journal, 2017, vol. 153

Référence DOI : 10.3847/1538-3881/153/2/72
Référence ADS : 2017AJ....153...72V

Résumé :

Anhydrous pyroxene-rich interplanetary dust particles (IDPs) have been proposed as surface analogs for about two-thirds of all C-complex asteroids. However, this suggestion appears to be inconsistent with the presence of hydrated silicates on the surfaces of some of these asteroids, including Ceres. Here, we report the presence of enstatite (pyroxene) on the surface of two C-type asteroids (Ceres and Eugenia) based on their spectral properties in the mid-infrared range. The presence of this component is particularly unexpected in the case of Ceres, because most thermal evolution models predict a surface consisting of hydrated compounds only. The most plausible scenario is that Ceres' surface has been partially contaminated by exogenous enstatite-rich material, possibly coming from the Beagle asteroid family. This scenario questions a similar origin for Ceres and the remaining C-types, and it possibly supports recent results obtained by the Dawn mission (NASA) that Ceres may have formed in the very outer solar system. Concerning the smaller D ˜ 200 km C-types such as Eugenia, both their derived surface composition (enstatite and amorphous silicates) and low density (

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