Binary asteroid (31) Euphrosyne: ice-rich and nearly spherical
- Creators
- Yang, B.
- Hanuš, J.
- Carry, B.
- Vernazza, P.
- Brož, M.
- Vachier, F.
- Rambaux, N.
- Marsset, M.
- Chrenko, O.
- Ševeček, P.
- Viikinkoski, M.
- Jehin, E.
- Ferrais, M.
- Podlewska-Gaca, E.
- Drouard, A.
- Marchis, F.
- Birlan, M.
- Benkhaldoun, Z.
- Berthier, J.
- Bartczak, P.
- Dumas, C.
- Dudziński, G.
- Ďurech, J.
- Castillo-Rogez, J.
- Cipriani, F.
- Colas, F.
- Fetick, R.
- Fusco, T.
- Grice, J.
- Jorda, Laurent
- Kaasalainen, M.
- Kryszczynska, A.
- Lamy, Philippe
- Marciniak, A.
- Michalowski, T.
- Michel, Patrick
- Pajuelo, M.
- Santana-Ros, T.
- Tanga, P.
- Vigan, A.
- Witasse, Olivier
- Others:
- European Southern Observatory [Santiago] (ESO) ; European Southern Observatory (ESO)
- Institute of Astronomy [Prague] ; Charles University [Prague] (CU)
- Joseph Louis LAGRANGE (LAGRANGE) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
- Laboratoire d'Astrophysique de Marseille (LAM) ; Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)
- Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE) ; Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
- Department of Earth, Atmospheric and Planetary Sciences [MIT, Cambridge] (EAPS) ; Massachusetts Institute of Technology (MIT)
- University of Tampere [Finland]
- Space Sciences, Technologies and Astrophysics Research Institute (STAR) ; Université de Liège
- Astronomical Observatory [Poznan] ; Adam Mickiewicz University in Poznań (UAM)
- Search for Extraterrestrial Intelligence Institute (SETI)
- Astronomical Institute of Romanian Academy ; Romanian Academy
- Oukaimeden Observatory ; Université Cadi Ayyad [Marrakech] (UCA)
- Thirty Meter Telescope Observatory
- Jet Propulsion Laboratory (JPL) ; NASA-California Institute of Technology (CALTECH)
- European Space Research and Technology Centre (ESTEC) ; European Space Agency (ESA)
- DOTA, ONERA, Université Paris Saclay [Palaiseau] ; ONERA-Université Paris-Saclay
- School of Physical Sciences [Milton Keynes] ; Faculty of Science, Technology, Engineering and Mathematics [Milton Keynes] ; The Open University [Milton Keynes] (OU)-The Open University [Milton Keynes] (OU)
- PLANETO - LATMOS ; Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS) ; Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
- Pontificia Universidad Católica del Perú = Pontifical Catholic University of Peru (PUCP)
- Universidad de Alicante
- Institut de Ciencies del Cosmos (ICCUB) ; Universitat de Barcelona (UB)
Description
Aims. Asteroid (31) Euphrosyne is one of the biggest objects in the asteroid main belt and it is also the largest member of its namesake family. The Euphrosyne family occupies a highly inclined region in the outer main belt and contains a remarkably large number of members, which is interpreted as an outcome of a disruptive cratering event.Methods. The goals of this adaptive-optics imaging study are threefold: to characterize the shape of Euphrosyne, to constrain its density, and to search for the large craters that may be associated with the family formation event.Results. We obtained disk-resolved images of Euphrosyne using SPHERE/ZIMPOL at the ESO 8.2 m VLT as part of our large program (ID: 199.C-0074, PI: Vernazza). We reconstructed its 3D shape via the ADAM shape modeling algorithm based on the SPHERE images and the available light curves of this asteroid. We analyzed the dynamics of the satellite with the Genoid meta-heuristic algorithm. Finally, we studied the shape of Euphrosyne using hydrostatic equilibrium models.Conclusions. Our SPHERE observations show that Euphrosyne has a nearly spherical shape with the sphericity index of 0.9888 and its surface lacks large impact craters. Euphrosyne's diameter is 268 ± 6 km, making it one of the top ten largest main belt asteroids. We detected a satellite of Euphrosyne – S/2019 (31) 1 – that is about 4 km across, on a circular orbit. The mass determined from the orbit of the satellite together with the volume computed from the shape model imply a density of 1665 ± 242 kg m−3, suggesting that Euphrosyne probably contains a large fraction of water ice in its interior. We find that the spherical shape of Euphrosyne is a result of the reaccumulation process following the impact, as in the case of (10) Hygiea. However, our shape analysis reveals that, contrary to Hygiea, the axis ratios of Euphrosyne significantly differ from those suggested by fluid hydrostatic equilibrium following reaccumulation.
Abstract
International audience
Additional details
- URL
- https://hal-insu.archives-ouvertes.fr/insu-02941038
- URN
- urn:oai:HAL:insu-02941038v1
- Origin repository
- UNICA