J/A+A/650/A129ivo://CDS.VizieR/J/A+A/650/A129doi:10.26093/cds/vizier.36500129CDSCarry B.Vernazza P.Vachier F.Neveu M.Berthier J.Hanus J.,Ferrais M.Jorda L.Marsset M.Viikinkoski M.Bartczak P.,Behrend R.Benkhaldoun Z.Birlan M.Castillo-Rogez J.Cipriani F.,Colas F.Drouard A.Dudzinski G. P.Desmars J.Dumas C. Durech J.,Fetick R.Fusco T.Grice J.Jehin E.Kaasalainen M.Kryszczynska A.,Lamy P.Marchis F.Marciniak A.Michalowski T.Michel P.Pajuelo M.,Podlewska-Gaca E.Rambaux N.Santana-Ros T.Storrs A.Tanga P.,Vigan A.Warner B.Wieczorek M.Witasse O.Yang B.2021-09-29T08:51:25Z2021-06-17T07:44:41ZCDS support team

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

cds-question@unistra.frsolar-systemasteroidsDynamical models of Solar System evolution have suggested that the so-called P- and D-type volatile-rich asteroids formed in the outer Solar System beyond Neptune's orbit and may be genetically related to the Jupiter Trojans, comets, and small Kuiper belt objects (KBOs). Indeed, the spectral properties of P- and D-type asteroids resemble that of anhydrous cometary dust. We aim to gain insights into the above classes of bodies by characterizing the internal structure of a large P- and D-type asteroid. We report high-angular-resolution imaging observations of the P-type asteroid (87) Sylvia with the the Very Large Telescope (VLT) Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument. These images were used to reconstruct the 3D shape of Sylvia. Our images together with those obtained in the past with large ground-based telescopes were used to study the dynamics of its two satellites. We also modeled Sylvia's thermal evolution. The shape of Sylvia appears flattened and elongated (a/b~1.45; a/c~1.84). We derive a volume-equivalent diameter of 271+/-5km and a low density of 1378+/-45kg/m^3^. The two satellites orbit Sylvia on circular, equatorial orbits. The oblateness of Sylvia should imply a detectable nodal precession which contrasts with the fully-Keplerian dynamics of its two satellites. This reveals an inhomogeneous internal structure, suggesting that Sylvia is differentiated. Sylvia's low density and differentiated interior can be explained by partial melting and mass redistribution through water percolation. The outer shell should be composed of material similar to interplanetary dust particles (IDPs) and the core should be similar to aqueously altered IDPs or carbonaceous chondrite meteorites such as the Tagish Lake meteorite. Numerical simulations of the thermal evolution of Sylvia show that for a body of such a size, partial melting was unavoidable due to the decay of long-lived radionuclides. In addition, we show that bodies as small as 130-150km in diameter should have followed a similar thermal evolution, while smaller objects, such as comets and the KBO Arrokoth, must have remained pristine, which is in agreement with in situ observations of these bodies. NASA Lucy mission target (617) Patroclus (diameter ~140km) may, however, be differentiated.2021A&A...650A.129Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/650/A129CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/650/A129https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/650/A129http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/650/A129https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/650/A129https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/650/A129http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/650/A129GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/650/A129/list (List of fits images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/650/A129/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/650/A129/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/650/A129/list?GETtext/xml+votable180.050000true60.435914.9470.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/650/A1296/279 297 300 304 20066 20073https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/650/A129?format=asciidefaultJ/A+A/650/A129/tablea1Table A1 (lightcurves)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIdLightcurve identifiermeta.idintObs.dateDate of observationtime.epochnullableDurLength of the lightcurvestime.intervalfloatNpointsNumber of measurements in the lightcurvemeta.numberintPhasePhase angle at the time of observationsdegpos.phaseAngfloatFilterFilter usedinstr.setup;instr.filtercharrmsRoot mean square residualsstat.errorfloatIAUCodeIAU Observatory Codemeta.code;instr.obstycharObserverBibcode or observer namemeta.bib.bibcodecharJ/A+A/650/A129/tableb1List of observers of the five stellar occultationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs.dateOccultation datetime.epochnullableObserverObserver namemeta.id;obs.observercharJ/A+A/650/A129/tablec1Table C1 (astrometry Romulus)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsDate of observationstime.epochnullableTelTelescope usedinstr.setupcharCameraCamera usedmeta.id;instrcharFilterFilter usedinstr.setup;instr.filtercharXoSatellite position along RAmaspos;instr.obstyfloatYoSatellite position along Decmaspos.eq.dec;arith.difffloatXomcSatellite residuals along RAmasstat.fit.residualfloatYomcSatellite residuals along Decmasstat.fit.residualfloatsigmaUncertaintymasstat.errorfloatdeltamag? Satellite differential magnitudemagphot.mag;arith.difffloatnullablee_deltamag? Uncertainty on the differential magnitudemagstat.errorfloatnullableJ/A+A/650/A129/tablec2Table C2 (astrometry Remus)FilterFilter usedinstr.setup;instr.filtercharCameraCamera usedmeta.id;instrcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObsDate of observationstime.epochnullableTelTelescope usedinstr.setupcharXoSatellite position along RAmaspos;instr.obstyfloatYoSatellite position along Decmaspos.eq.dec;arith.difffloatXomcSatellite residuals along RAmasstat.fit.residualfloatYomcSatellite residuals along Decmasstat.fit.residualfloatsigmaUncertaintymasstat.errorfloatdeltamag? Satellite differential magnitudemagphot.mag;arith.difffloatnullablee_deltamag? Uncertainty on the differential magnitudemagstat.errorfloatnullableJ/A+A/650/A129/listList of fits imagesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintObs.dateObservation datestime.epoch;obsnullablesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitschar