J/A+A/670/A52ivo://CDS.VizieR/J/A+A/670/A52doi:10.26093/cds/vizier.36700052CDSMarsset M.Broz M.Vermersch J.Rambaux N.Ferrais M.Viikinkoski M.,Hanus J.Jehin E.Podlewska-Gaca E.Bartczak P.Dudzinski G.Carry B.,Vernazza P.Szakats R.Duffard R.Jones A.Molina D.Santana-Ros T.,Benkhaldoun Z.Birlan M.Dumas C.Fetick R.Fusco T.Jorda L.,Marchis F.Vachier F.Yang B.2024-11-06T20:02:42Z2023-02-03T08:00:23ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frsolar-systemasteroidsgalaxy-classification-systemsvisible-astronomyCybele asteroids constitute an appealing reservoir of primitive material genetically linked to the outer Solar System, and the physical properties (size and shape) of the largest members can be readily accessed by large (8m class) telescopes. We took advantage of the bright apparition of the most iconic member of the Cybele population, (65) Cybele, in July and August 2021 to acquire high-angular-resolution images and optical light curves of the asteroid with which we aim to analyse its shape and bulk properties. Eight series of images were acquired with VLT/SPHERE+ZIMPOL, seven of which were combined with optical light curves to reconstruct the shape of the asteroid using the ADAM, MPCD, and SAGE algorithms. The origin of the shape was investigated by means of N-body simulations. Cybele has a volume-equivalent diameter of 263+/-3km and a bulk density of 1.55+/-0.19g/cm^3^. Notably, its shape and rotation state are closely compatible with those of a Maclaurin equilibrium figure. The lack of a collisional family associated with Cybele and the higher bulk density of that body with respect to other large P-type asteroids suggest that it never experienced any large disruptive impact followed by rapid re-accumulation. This would imply that its present-day shape represents the original one. However, numerical integration of the long-term dynamical evolution of a hypothetical family of Cybele shows that it is dispersed by gravitational perturbations and chaotic diffusion over gigayears of evolution. The very close match between Cybele and an equilibrium figure opens up the possibility that D>=260km (M>=1.5x10^19^kg) small bodies from the outer Solar System all formed at equilibrium. However, we cannot currently rule out an old impact as the origin of the equilibrium shape of Cybele. Cybele itself is found to be dynamically unstable, implying that it was "recently" (<1Gyr ago) placed on its current orbit either through slow diffusion from a relatively stable orbit in the Cybele region or, less likely, from an unstable, Jupiter-family-comet orbit in the planet-crossing region.2023A&A...670A..52Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/670/A52CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/618/A154 : (89) Julia SPHERE/ZIMPOL images (Vernazza+, 2018)J/A+A/619/L3 : (16) Psyche images (Viikinkoski+, 2018)J/A+A/623/A6 : Vesta VLT/SPHERE/ZIMPOL images (Fetick+, 2019)J/A+A/623/A132 : (41) Daphne SPHERE/ZIMPOL images (Carry+, 2019)J/A+A/624/A121 : (7) Iris Deconvolved disk-resolved images (Hanus+, 2019)J/A+A/633/A65 : (704) Interamnia images (Hanus+, 2020)J/A+A/638/L15 : (16) Psyche. VLT/SPHERE images & shape models (Ferrais+, 2020)J/A+A/641/A80 : (31) Euphrosyne R-band images (Yang+, 2020)J/A+A/650/A129 : (87) Sylvia SPHERE images (Carry+, 2021)J/A+A/653/A57 : (216) Kleopatra images (Marchis+, 2021)J/A+A/662/A71 : (22) Kalliope images (Ferrais+, 2022)http://astro.troja.mff.cuni.cz/projects/asteroids3D/web.php : DAMIT Home Pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/670/A52https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/670/A52http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/670/A52https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/670/A52https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/670/A52http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/670/A52GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticaldefaultJ/A+A/670/A52/tablea1VLT/SPHERE disk-resolved images obtained in the N_R filter with the ZIMPOL camerarecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs.dateObservation date (UT)stime.epoch;obsnullableExpExposure time (1)stime.duration;obs.exposureintAirmassAirmassobs.airMassfloatDeltaDistance to the EarthAUpos.distancefloatrDistance to the SunAUpos.distance;pos.heliocentricfloatalphaPhase angledegsrc.orbitalfloatDaAngular diameterarcsecphys.angSizefloatlambdasubESub-Earth point longitudedegpos.earth.lonfloatbetasubESub-Earth point latitudedegpos.ecliptic.latfloatCamCamerameta.id;instrcharFileName1Deconvolved fits image filename in subdirectory fitsmeta.id;meta.fitscharFileName2Reduced fits images filename in subdirectory fitsmeta.id;meta.fitschar