J/A+A/670/L25ivo://CDS.VizieR/J/A+A/670/L25doi:10.26093/cds/vizier.36709025CDSLainey V.Rambaux N.Cooper N.Dahoumane R.Zhang Q.2024-11-28T20:02:18Z2023-02-24T08:08:06ZCDS support team

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

cds-question@unistra.frsolar-systemsolar-system-planetsastrometryThe Cassini-Huygens space mission provided a huge amount of data for the Saturnian system. While the mission ended in September 2017, there is still much information to be retrieved from the data. Here, from their orbital motion, we infer the interior of the five inner Saturnian moons, Atlas, Prometheus, Pandora, Janus, and Epimetheus. Our results benefit from a recent study of the shape of these moons, which provides a much better estimation of their 3D shape and volume. Using Cassini Imaging Science Subsystem (ISS) astrometric data, we again reduced the Cassini ISS images with an improved shape modelling. We then integrated the orbital motion of the inner Saturnian moons and solved for a large set of physical parameters for this system, including the masses and physical libration amplitudes of the moons. We obtain a density value (in g/cm^3^ with a 1{sigma} error bar based on the digital terrain models and spherical harmonics available today) of 0.3935+/-0.0033, 0.4873+/-0.0026, 0.5045+/-0.0017, 0.6233+/-0.0015, and 0.6413+/-0.0002 for Atlas, Prometheus, Pandora, Epimetheus, and Janus, respectively. We were able to determine the physical libration amplitudes of Prometheus, Pandora, Epimetheus, and Janus to be 0.98+/-0.08, -5.2+/-0.7, -6.0+/-0.6, and -0.39+/-0.16 (degrees and 1{sigma} error bar), respectively. Our solutions for Epimetheus and Janus are in full agreement with a former estimation performed directly from the measurement of the rotation of these two moons. We confirm the large porosity of these five moons and their increase in density as a function of their size. Our estimations of the physical librations of Prometheus, Pandora, Janus, and Epimetheus are consistent with a homogeneous interior, but for Pandora a heterogeneous interior is also plausible.2023A&A...670L..25Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/670/L25CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+AS/121/65 : 1990-1994 Saturn's satellites astrometry (Harper+ 1997)J/A+AS/136/257 : Saturn's satellites in 1995/97 (Harper+ 1999)J/A+AS/139/305 : Position of Saturn's satellites (1982-1988) (Veiga+, 1999)J/A+A/422/377 : 1997-2000 Saturn's satellites astrometry (Qiao+, 2004)J/A+A/493/1183 : Saturn major satellites observations (1874-2007)J/AJ/136/2214 : Positions of Saturn and its satellites in 2002-2006J/AJ/149/27 : Cassini ISS astrometry of Saturnian satellitesJ/other/KFNT/33.70 : Topocentric positions of Saturn's moonsJ/AJ/159/129 : 21 saturnian small moons brightness with ISSJ/ApJS/263/15 : Cassini Visual + IR obs. of Saturn + Jupiterhttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/670/L25https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/670/L25http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/670/L25https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/670/L25https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/670/L25http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/670/L25GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/670/L25/dataAstrometric ISS/Cassini data of the five inner moons of SaturnrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateDate of observation (TDB)time.epochnullableTimeFraction of day of observation (TDB)dtime.epochdoublePAtlasS? Position of moon Atlas (sample)pixpos.eqdoublenullablee_PAtlasS? 1{sigma} uncertainty on position of moon Atlas (sample)pixstat.errorfloatnullablePAtlasL? Position of moon Atlas (line)pixpos.eqdoublenullablee_PAtlasL? 1{sigma} uncertainty on position of moon Atlas (line)pixstat.errorfloatnullablePPrometheusS? Position of moon Prometheus (sample)pixpos.eqdoublenullablee_PPrometheusS? 1{sigma} uncertainty on position of moon Prometheus (sample)pixstat.errorfloatnullablePPrometheusL? Position of moon Prometheus (line)pixpos.eqdoublenullablee_PPrometheusL? 1{sigma} uncertainty on position of moon Prometheus (line)pixstat.errorfloatnullablePPandoraS? Position of moon Pandora (sample)pixpos.eqdoublenullablee_PPandoraS? 1{sigma} uncertainty on position of moon Pandora (sample)pixstat.errorfloatnullablePPandoraL? Position of moon Pandora (line)pixpos.eqdoublenullablee_PPandoraL? 1{sigma} uncertainty on position of moon Pandora (line)pixstat.errorfloatnullablePEpimetheusS? Position of moon Epimetheus (sample)pixpos.eqdoublenullablee_PEpimetheusS? 1{sigma} uncertainty on position of moon Epimetheus (sample)pixstat.errorfloatnullablePEpimetheusL? Position of moon Epimetheus (line)pixpos.eqfloatnullablee_PEpimetheusL? 1{sigma} uncertainty on position of moon Epimetheus (line)pixstat.errorfloatnullablePJanusS? Position of moon Janus (sample)pixpos.eqdoublenullablee_PJanusS? 1{sigma} uncertainty on position of moon Janus (sample)pixstat.errorfloatnullablePJanusL? Position of moon Janus (line)pixpos.eqdoublenullablee_PJanusL? 1{sigma} uncertainty on position of moon Janus (line)pixstat.errorfloatnullableDirXDirection of the center of the camera framedegpos.cartesian.x;instr.detdoubleDirYDirection of the center of the camera framedegpos.cartesian.y;instr.detdoubleTwistTwist angledeginstr.offsetdoubleFlenghtFocal length of the cameramminstr.paramdoubleXposCenter coordinate of the field of viewpixpos.cartesian.x;instr.detfloatYposCenter coordinate of the field of viewpixpos.cartesian.y;instr.detfloat