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Title: DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS

Abstract

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 (<1.5 g cm{sup −3}) suggest that these bodies accreted from the same building blocks, namely chondritic porous, pyroxene-rich IDPs and volatiles (mostly water ice), and that amore » significant volume fraction of these bodies has remained unaffected by hydrothermal activity likely implying a late accretion. In addition, their current heliocentric distance may best explain the presence or absence of water ice at their surfaces. Finally, we raise the possibility that CI chondrites, Tagish-Lake-like material, or hydrated IDPs may be representative samples of the cores of these bodies.« less

Authors:
; ; ; ; ; ;  [1];  [2];  [3];  [4]; ; ;  [5]; ;  [6];  [7];  [8];  [9]
  1. Aix Marseille Univ, CNRS, LAM, Laboratoire d’Astrophysique de Marseille, Marseille (France)
  2. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
  3. UJF-Grenoble 1, CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), UMR 5274, Grenoble F-38041 (France)
  4. Department of Earth and Planetary Sciences and Planetary Geosciences Institute, University of Tennessee, Knoxville, TN 37996-1410 (United States)
  5. Institut d’Astrophysique Spatiale, CNRS, UMR-8617, Université Paris-Sud, bâtiment 121, F-91405 Orsay Cedex (France)
  6. Laboratoire Lagrange, UNS-CNRS, Observatoire de la Cote d’Azur, Boulevard de l’Observatoire-CS 34229, F-06304 Nice Cedex 4 (France)
  7. Carl Sagan Center at the SETI Institute, Mountain View, CA 94043 (United States)
  8. IMCCE, Observatoire de Paris, 77 avenue Denfert-Rochereau, F-75014 Paris Cedex (France)
  9. SMIS Beamline, Soleil Synchrotron, BP48, L’Orme des Merisiers, F-91192 Gif sur Yvette Cedex (France)
Publication Date:
OSTI Identifier:
22663992
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (Online); Journal Volume: 153; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTEROIDS; ASTROPHYSICS; CARBON COMPLEXES; CHONDRITES; DATA ANALYSIS; ENSTATITE; EVOLUTION; METEOROIDS; NASA; PLANETS; POROUS MATERIALS; SILICATES; SOLAR SYSTEM; SURFACES; WATER

Citation Formats

Vernazza, P., Marsset, M., Groussin, O., Lamy, P., Jorda, L., Mousis, O., Delsanti, A., Castillo-Rogez, J., Beck, P., Emery, J., Brunetto, R., Djouadi, Z., Dionnet, Z., Delbo, M., Carry, B., Marchis, F., Zanda, B., and Borondics, F., E-mail: pierre.vernazza@lam.fr. DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS. United States: N. p., 2017. Web. doi:10.3847/1538-3881/153/2/72.
Vernazza, P., Marsset, M., Groussin, O., Lamy, P., Jorda, L., Mousis, O., Delsanti, A., Castillo-Rogez, J., Beck, P., Emery, J., Brunetto, R., Djouadi, Z., Dionnet, Z., Delbo, M., Carry, B., Marchis, F., Zanda, B., & Borondics, F., E-mail: pierre.vernazza@lam.fr. DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS. United States. doi:10.3847/1538-3881/153/2/72.
Vernazza, P., Marsset, M., Groussin, O., Lamy, P., Jorda, L., Mousis, O., Delsanti, A., Castillo-Rogez, J., Beck, P., Emery, J., Brunetto, R., Djouadi, Z., Dionnet, Z., Delbo, M., Carry, B., Marchis, F., Zanda, B., and Borondics, F., E-mail: pierre.vernazza@lam.fr. Wed . "DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS". United States. doi:10.3847/1538-3881/153/2/72.
@article{osti_22663992,
title = {DIFFERENT ORIGINS OR DIFFERENT EVOLUTIONS? DECODING THE SPECTRAL DIVERSITY AMONG C-TYPE ASTEROIDS},
author = {Vernazza, P. and Marsset, M. and Groussin, O. and Lamy, P. and Jorda, L. and Mousis, O. and Delsanti, A. and Castillo-Rogez, J. and Beck, P. and Emery, J. and Brunetto, R. and Djouadi, Z. and Dionnet, Z. and Delbo, M. and Carry, B. and Marchis, F. and Zanda, B. and Borondics, F., E-mail: pierre.vernazza@lam.fr},
abstractNote = {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 (<1.5 g cm{sup −3}) suggest that these bodies accreted from the same building blocks, namely chondritic porous, pyroxene-rich IDPs and volatiles (mostly water ice), and that a significant volume fraction of these bodies has remained unaffected by hydrothermal activity likely implying a late accretion. In addition, their current heliocentric distance may best explain the presence or absence of water ice at their surfaces. Finally, we raise the possibility that CI chondrites, Tagish-Lake-like material, or hydrated IDPs may be representative samples of the cores of these bodies.},
doi = {10.3847/1538-3881/153/2/72},
journal = {Astronomical Journal (Online)},
number = 2,
volume = 153,
place = {United States},
year = {Wed Feb 01 00:00:00 EST 2017},
month = {Wed Feb 01 00:00:00 EST 2017}
}