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Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2021

VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis

1 LAM - Laboratoire d'Astrophysique de Marseille
2 Institute of Astronomy [Prague]
3 UniCA - Université Côte d'Azur
4 EAPS - Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge]
5 UK - Univerzita Karlova [Praha, Česká republika] = Charles University [Prague, Czech Republic]
6 TUT - Tampere University of Technology [Tampere]
7 SETI - Search for Extraterrestrial Intelligence Institute
8 IMCCE - Institut de Mécanique Céleste et de Calcul des Ephémérides
9 Astronomical Institute of Romanian Academy
10 UAM - Uniwersytet im. Adama Mickiewicza w Poznaniu = Adam Mickiewicz University in Poznań
11 IRHS - Institut de Recherche en Horticulture et Semences
12 Université de Liège
13 IPAG - Institut de Planétologie et d'Astrophysique de Grenoble
14 CALTECH - California Institute of Technology
15 ESA - Agence Spatiale Européenne = European Space Agency
16 OU - The Open University [Milton Keynes]
17 Department of Mathematics [Tampere]
18 University of Maryland [College Park]
19 LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
20 HCL - Hospices Civils de Lyon
21 RESHAPE - Inserm U1290 - UCBL1 - Research on Healthcare Performance
22 Universidad de Alicante
23 UB - Universitat de Barcelona
24 ESO - European Southern Observatory [Santiago]
25 OSU PYTHEAS - Institut Pythéas
26 OHP - Observatoire de Haute-Provence
27 Geneva Observatory
28 UCA - Université Cadi Ayyad [Marrakech]
29 HCTI - Héritages et Constructions dans le Texte et l'Image
30 Observatoire du Bois de Bardon
31 Association T60, Observatoire Midi-Pyrénées
32 LSR - Laboratory for Space Research [Hong Kong]
33 IAS - Institut d'astrophysique spatiale
34 KASI - Korea Astronomy and Space Science Institute
35 Chungbuk National University
36 Larefi - Laboratoire d'analyse et de recherche en économie et finance internationales
37 IAP - Institut d'Astrophysique de Paris
38 Sanofi-Aventis R&D
39 PSI - Planetary Science Institute [Tucson]
M. Ferrais
L. Jorda
J. Hanuš
B. Carry
E. Jehin
C. Dumas
P. Tanga
  • Fonction : Auteur
A. Vigan
B. Yang
P. Antonini
  • Fonction : Auteur
M. Audejean
  • Fonction : Auteur
R. Behrend
  • Fonction : Auteur
J. M. Bosch
  • Fonction : Auteur
A. Chapman
  • Fonction : Auteur
D. Molina
  • Fonction : Auteur
R. Montaigut
  • Fonction : Auteur
J. Oey
  • Fonction : Auteur
N. Payre
  • Fonction : Auteur
A. G. Sanchez
  • Fonction : Auteur
L. Socha
  • Fonction : Auteur

Résumé

Context. Until recently, the 3D shape, and therefore density (when combining the volume estimate with available mass estimates), and surface topography of the vast majority of the largest (D  ≥ 100 km) main-belt asteroids have remained poorly constrained. The improved capabilities of the SPHERE/ZIMPOL instrument have opened new doors into ground-based asteroid exploration.Aims. To constrain the formation and evolution of a representative sample of large asteroids, we conducted a high-angular-resolution imaging survey of 42 large main-belt asteroids with VLT/SPHERE/ZIMPOL. Our asteroid sample comprises 39 bodies with D  ≥ 100 km and in particular most D  ≥ 200 km main-belt asteroids (20/23). Furthermore, it nicely reflects the compositional diversity present in the main belt as the sampled bodies belong to the following taxonomic classes: A, B, C, Ch/Cgh, E/M/X, K, P/T, S, and V.Methods. The SPHERE/ZIMPOL images were first used to reconstruct the 3D shape of all targets with both the ADAM and MPCD reconstruction methods. We subsequently performed a detailed shape analysis and constrained the density of each target using available mass estimates including our own mass estimates in the case of multiple systems.Results. The analysis of the reconstructed shapes allowed us to identify two families of objects as a function of their diameters, namely “spherical” and “elongated” bodies. A difference in rotation period appears to be the main origin of this bimodality. In addition, all but one object (216 Kleopatra) are located along the Maclaurin sequence with large volatile-rich bodies being the closest to the latter. Our results further reveal that the primaries of most multiple systems possess a rotation period of shorter than 6 h and an elongated shape (c∕a ≤ 0.65). Densities in our sample range from ~1.3 g cm−3 (87 Sylvia) to ~4.3 g cm−3 (22 Kalliope). Furthermore, the density distribution appears to be strongly bimodal with volatile-poor (ρ ≥ 2.7 g cm−3) and volatile-rich (ρ ≤ 2.2 g cm−3) bodies. Finally, our survey along with previous observations provides evidence in support of the possibility that some C-complex bodies could be intrinsically related to IDP-like P- and D-type asteroids, representing different layers of a same body (C: core; P/D: outer shell). We therefore propose that P/ D-types and some C-types may have the same origin in the primordial trans-Neptunian disk.
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hal-03375585 , version 1 (12-10-2021)

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P. Vernazza, M. Ferrais, L. Jorda, J. Hanuš, B. Carry, et al.. VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy and Astrophysics - A&A, 2021, 654, pp.A56. ⟨10.1051/0004-6361/202141781⟩. ⟨hal-03375585⟩
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