DOCSLIB.ORG

Some of Saturn's Small Satellites Have

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Some of Saturn's Small Satellites Have 51st Lunar and Planetary Science Conference (2020) 1477.pdf SOME OF SATURN’S SMALL SATELLITES HAVE SURPRISINGLY STYGIAN OR STRANGELY SNOWY SURACES. M.M. Hedman1, P. Helfenstein2, R.O. Chancia1, P. Thomas2, E. Roussos3, C. Paranicas4, A.J. VerBiscer5, 1Department of Physics, University of Idaho, Moscow ID 83844, 2Cornell Center for Astrophysics and Planetary Science, Cornell Universit, Ithaca NY 14853, 3Max Planck Institute or Solar System Research, Goettingen, Germany 37077, 4APL, Johns Hopkins University, Laurel MD 20723, 6Department of Astronomy, University of Virginia, Charlottesville VA 22904. The Saturn system contains a large numBer of any other nearby moon, despite orbiting within the inner moons with a range of surface features and photometric flank of the E ring. properties that, in part, reflect various aspects of their The comparatively dark surfaces of Methone, Pal- environments. In particular, the whole-disk albedos of lene and Aegaeon imply that something Besides the E the mid-sized icy moons Mi- mas, Enceladus, Tethys, ring is affecting their surface properties, and we pro- Dione and Rhea are strongly correlated with the pose that the most likely explanation are Saturn’s expected fluxes of the E-ring particles that surround all radiation belts. Cassini measured high fluxes of high- of these moons [1, 2]. Since the E-ring originates from energy (> 25 MeV) protons Between the orBits of the Enceladus’ plume, this correlation means that larger moons Janus/Epimetheus, Mimas and Enceladus Enceladus’ geological activity strongly affects the [5]. These four moons are all large enough that they surface properties of Saturn’s mid-sized moons [1]. create persistent regions of low energetic proton flux However, these mid-sized moons are not the only along their orbits known as macrosignatures, and so objects in this region. Much smaller moons can Be found their surface weathering is limited By the slow ra- dial at several locations between the main rings and Mimas’ diffusion that works to fill in the macrosignature. By orbit (Janus, Epimetheus and Aegaeon), be- tween the contrast, Aegaeon, Methone and Pallene are too small orbits of Mimas and Enceladus (Methone, Anthe and to produce such depletions and so orbit in regions with Pallene), and along the orbits of Tethys and Dione much higher fluxes of energetic protons, and so are (Telesto, Calypso, Helene and Polydeuces). These weathered at a much higher rate. The ex- act mechanism moons lack much of the internal processes operating by which this radiation darkens the sur- faces of these inside the mid-sized moons and might Be expected to small moons is still not completely clear. However, provide a fiducial for testing models of how much further investigations of both the spectral and various internal and external processes affect satellite photometric properties of these and other satellites surface properties For example, hese moons are also should help clarify how radiation affects the surfaces of embedded in the E ring and so one might expect their icy moons in the outer Solar System. surface Brightnesses to follow the same trends as their On the other hand, we also find that Calypso and larger neighBors. However, quantitatively testing this Helene have substantially brighter surfaces than their hypothesis with albedos obtained from availaBle Cassini co-orbital companions Tethys and Dione. This suggests imaging data is a challenge, firstly Because these smaller that Calypso and Helene might have experienced higher moons have significantly non-spherical shapes [3], and particle fluxes, But there are no oBvious structures in the secondly Because most of the observational geometry E ring that would preferentially Brighten these particular coverage needed to accurately constrain models of their moons, so there must either Be something suBtle in the photometric behavior are low spatial resolution images E-ring particles’ orbital properties that leads to that are suitaBle only for disk-integrated measurements suBstantial asymmetries in the particle flux, or [4]. something happened recently to temporarily increase We have developed a new disk-integrated both these moons’ brightnesses. photometric model that explicitly accounts for the smoothly ellipsoidal shapes of the small moons and thus [1] Verbiscer, A., et al. (2007) Science, 315, 815. [2] allows us to derive estimates of whole-disk albedos that Hendrix, A., et al. (2018) Icarus, 300, 103-114. [3] can be compared Between moons of different shapes [5]. Thomas, P., et al. (2018) in Enceladus and the Icy We find that Aegaeon, Methone and Pallene are Moons of Saturn, P. Schenk, R. Clark, C. Howett, A. surprisingly dark at visiBle wavelengths. More VerBiscer, H. Waite, Eds. [4] Verbiscer, A., et al. specifically, Methone and Pallene are darker than (2018) in Enceladus and the Icy Moons of Saturn, P. Mimas. This result was unexpected Because Both of Schenk, R. Clark, C. Howett, A. Verbiscer, H. Waite, these moons orbit Between Mimas and Enceladus, and Eds. [5] Hedman, M.M. et al. (2019) arXiv: so the E-ring flux is higher onto these moons than it is 1912:09192, accepted for publication in AJ. [6] onto Mimas, which would naturally tend to make them Kollmann,P. et al. (2013), Icarus, 222, 323-341. brighter. Aegaeon is even more extreme, being about as dark as Iapetus’ leading side and thus much darker than .
Load more

Recommended publications
  • Arxiv:1912.09192V2 [Astro-Ph.EP] 24 Feb 2020
    Draft version February 25, 2020 Typeset using LATEX preprint style in AASTeX62 Photometric analyses of Saturn's small moons: Aegaeon, Methone and Pallene are dark; Helene and Calypso are bright. M. M. Hedman,1 P. Helfenstein,2 R. O. Chancia,1, 3 P. Thomas,2 E. Roussos,4 C. Paranicas,5 and A. J. Verbiscer6 1Department of Physics, University of Idaho, Moscow, ID 83844 2Cornell Center for Astrophysics and Planetary Science, Cornell University, Ithaca NY 14853 3Center for Imaging Science, Rochester Institute of Technology, Rochester NY 14623 4Max Planck Institute for Solar System Research, G¨ottingen,Germany 37077 5APL, John Hopkins University, Laurel MD 20723 6Department of Astronomy, University of Virginia, Charlottesville, VA 22904 ABSTRACT We examine the surface brightnesses of Saturn's smaller satellites using a photometric model that explicitly accounts for their elongated shapes and thus facilitates compar- isons among different moons. Analyses of Cassini imaging data with this model reveals that the moons Aegaeon, Methone and Pallene are darker than one would expect given trends previously observed among the nearby mid-sized satellites. On the other hand, the trojan moons Calypso and Helene have substantially brighter surfaces than their co-orbital companions Tethys and Dione. These observations are inconsistent with the moons' surface brightnesses being entirely controlled by the local flux of E-ring par- ticles, and therefore strongly imply that other phenomena are affecting their surface properties. The darkness of Aegaeon, Methone and Pallene is correlated with the fluxes of high-energy protons, implying that high-energy radiation is responsible for darkening these small moons. Meanwhile, Prometheus and Pandora appear to be brightened by their interactions with nearby dusty F ring, implying that enhanced dust fluxes are most likely responsible for Calypso's and Helene's excess brightness.
    [Show full text]
  • Cassini Update
    Cassini Update Dr. Linda Spilker Cassini Project Scientist Outer Planets Assessment Group 22 February 2017 Sols%ce Mission Inclina%on Profile equator Saturn wrt Inclination 22 February 2017 LJS-3 Year 3 Key Flybys Since Aug. 2016 OPAG T124 – Titan flyby (1584 km) • November 13, 2016 • LAST Radio Science flyby • One of only two (cf. T106) ideal bistatic observations capturing Titan’s Northern Seas • First and only bistatic observation of Punga Mare • Western Kraken Mare not explored by RSS before T125 – Titan flyby (3158 km) • November 29, 2016 • LAST Optical Remote Sensing targeted flyby • VIMS high-resolution map of the North Pole looking for variations at and around the seas and lakes. • CIRS last opportunity for vertical profile determination of gases (e.g. water, aerosols) • UVIS limb viewing opportunity at the highest spatial resolution available outside of occultations 22 February 2017 4 Interior of Hexagon Turning “Less Blue” • Bluish to golden haze results from increased production of photochemical hazes as north pole approaches summer solstice. • Hexagon acts as a barrier that prevents haze particles outside hexagon from migrating inward. • 5 Refracting Atmosphere Saturn's• 22unlit February rings appear 2017 to bend as they pass behind the planet’s darkened limb due• 6 to refraction by Saturn's upper atmosphere. (Resolution 5 km/pixel) Dione Harbors A Subsurface Ocean Researchers at the Royal Observatory of Belgium reanalyzed Cassini RSS gravity data• 7 of Dione and predict a crust 100 km thick with a global ocean 10’s of km deep. Titan’s Summer Clouds Pose a Mystery Why would clouds on Titan be visible in VIMS images, but not in ISS images? ISS ISS VIMS High, thin cirrus clouds that are optically thicker than Titan’s atmospheric haze at longer VIMS wavelengths,• 22 February but optically 2017 thinner than the haze at shorter ISS wavelengths, could be• 8 detected by VIMS while simultaneously lost in the haze to ISS.
    [Show full text]
  • Dynamics of Saturn's Small Moons in Coupled First Order Planar Resonances
    Dynamics of Saturn's small moons in coupled first order planar resonances Maryame El Moutamid Bruno Sicardy and St´efanRenner LESIA/IMCCE | Paris Observatory 26 juin 2012 Maryame El Moutamid ESLAB-2012 | ESA/ESTEC Noordwijk Saturn system Maryame El Moutamid ESLAB-2012 | ESA/ESTEC Noordwijk Very small moons Maryame El Moutamid ESLAB-2012 | ESA/ESTEC Noordwijk New satellites : Anthe, Methone and Aegaeon (Cooper et al., 2008 ; Hedman et al., 2009, 2010 ; Porco et al., 2005) Very small (0.5 km to 2 km) Vicinity of the Mimas orbit (outside and inside) The aims of the work A better understanding : - of the dynamics of this population of news satellites - of the scenario of capture into mean motion resonances Maryame El Moutamid ESLAB-2012 | ESA/ESTEC Noordwijk Dynamical structure of the system µ µ´ Mp We consider only : - The resonant terms - The secular terms causing the precessions of the orbit When µ ! 0 ) The symmetry is broken ) different kinds of resonances : - Lindblad Resonance - Corotation Resonance D'Alembert rules : 0 0 c = (m + 1)λ − mλ − $ 0 L = (m + 1)λ − mλ − $ Maryame El Moutamid ESLAB-2012 | ESA/ESTEC Noordwijk Corotation Resonance - Aegaeon (7/6) : c = 7λMimas − 6λAegaeon − $Mimas - Methone (14/15) : c = 15λMethone − 14λMimas − $Mimas - Anthe (10/11) : c = 11λAnthe − 10λMimas − $Mimas Maryame El Moutamid ESLAB-2012 | ESA/ESTEC Noordwijk Corotation resonances Mean motion resonance : n1 = m+q n2 m Particular case : Lagrangian Equilibrium Points Maryame El Moutamid ESLAB-2012 | ESA/ESTEC Noordwijk Adam's ring and Galatea Maryame
    [Show full text]
  • 7 Planetary Rings Matthew S
    7 Planetary Rings Matthew S. Tiscareno Center for Radiophysics and Space Research, Cornell University, Ithaca, NY, USA 1Introduction..................................................... 311 1.1 Orbital Elements ..................................................... 312 1.2 Roche Limits, Roche Lobes, and Roche Critical Densities .................... 313 1.3 Optical Depth ....................................................... 316 2 Rings by Planetary System .......................................... 317 2.1 The Rings of Jupiter ................................................... 317 2.2 The Rings of Saturn ................................................... 319 2.3 The Rings of Uranus .................................................. 320 2.4 The Rings of Neptune ................................................. 323 2.5 Unconfirmed Ring Systems ............................................. 324 2.5.1 Mars ............................................................... 324 2.5.2 Pluto ............................................................... 325 2.5.3 Rhea and Other Moons ................................................ 325 2.5.4 Exoplanets ........................................................... 327 3RingsbyType.................................................... 328 3.1 Dense Broad Disks ................................................... 328 3.1.1 Spiral Waves ......................................................... 329 3.1.2 Gap Edges and Moonlet Wakes .......................................... 333 3.1.3 Radial Structure .....................................................
    [Show full text]
  • Tidal Heating in Enceladus
    Icarus 188 (2007) 535–539 www.elsevier.com/locate/icarus Note Tidal heating in Enceladus Jennifer Meyer ∗, Jack Wisdom Massachusetts Institute of Technology, Cambridge, MA 02139, USA Received 20 February 2007; revised 3 March 2007 Available online 19 March 2007 Abstract The heating in Enceladus in an equilibrium resonant configuration with other saturnian satellites can be estimated independently of the physical properties of Enceladus. We find that equilibrium tidal heating cannot account for the heat that is observed to be coming from Enceladus. Equilibrium heating in possible past resonances likewise cannot explain prior resurfacing events. © 2007 Elsevier Inc. All rights reserved. Keywords: Enceladus; Saturn, satellites; Satellites, dynamics; Resonances, orbital; Tides, solid body 1. Introduction One mechanism for heating Enceladus that passes the Mimas test is the secondary spin–orbit libration model (Wisdom, 2004). Fits to the shape of Enceladus is a puzzle. Cassini observed active plumes emanating from Enceladus from Voyager images indicated that the frequency of small amplitude Enceladus (Porco et al., 2006). The plumes consist almost entirely of water oscillations about the Saturn-pointing orientation of Enceladus was about 1/3 vapor, with entrained water ice particles of typical size 1 µm. Models of the of the orbital frequency. In the phase-space of the spin–orbit problem near the plumes suggest the existence of liquid water as close as 7 m to the surface damped synchronous state the stable equilibrium bifurcates into a period-tripled (Porco et al., 2006). An alternate model has the water originate in a clathrate state. If Enceladus were trapped in this bifurcated state, then there could be sev- reservoir (Kieffer et al., 2006).
    [Show full text]
  • The Orbits of Saturn's Small Satellites Derived From
    The Astronomical Journal, 132:692–710, 2006 August A # 2006. The American Astronomical Society. All rights reserved. Printed in U.S.A. THE ORBITS OF SATURN’S SMALL SATELLITES DERIVED FROM COMBINED HISTORIC AND CASSINI IMAGING OBSERVATIONS J. N. Spitale CICLOPS, Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301; [email protected] R. A. Jacobson Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 C. C. Porco CICLOPS, Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 and W. M. Owen, Jr. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 Received 2006 February 28; accepted 2006 April 12 ABSTRACT We report on the orbits of the small, inner Saturnian satellites, either recovered or newly discovered in recent Cassini imaging observations. The orbits presented here reflect improvements over our previously published values in that the time base of Cassini observations has been extended, and numerical orbital integrations have been performed in those cases in which simple precessing elliptical, inclined orbit solutions were found to be inadequate. Using combined Cassini and Voyager observations, we obtain an eccentricity for Pan 7 times smaller than previously reported because of the predominance of higher quality Cassini data in the fit. The orbit of the small satellite (S/2005 S1 [Daphnis]) discovered by Cassini in the Keeler gap in the outer A ring appears to be circular and coplanar; no external perturbations are appar- ent. Refined orbits of Atlas, Prometheus, Pandora, Janus, and Epimetheus are based on Cassini , Voyager, Hubble Space Telescope, and Earth-based data and a numerical integration perturbed by all the massive satellites and each other.
    [Show full text]
  • Titan and the Moons of Saturn Telesto Titan
    The Icy Moons and the Extended Habitable Zone Europa Interior Models Other Types of Habitable Zones Water requires heat and pressure to remain stable as a liquid Extended Habitable Zones • You do not need sunlight. • You do need liquid water • You do need an energy source. Saturn and its Satellites • Saturn is nearly twice as far from the Sun as Jupiter • Saturn gets ~30% of Jupiter’s sunlight: It is commensurately colder Prometheus • Saturn has 82 known satellites (plus the rings) • 7 major • 27 regular • 4 Trojan • 55 irregular • Others in rings Titan • Titan is nearly as large as Ganymede Titan and the Moons of Saturn Telesto Titan Prometheus Dione Titan Janus Pandora Enceladus Mimas Rhea Pan • . • . Titan The second-largest moon in the Solar System The only moon with a substantial atmosphere 90% N2 + CH4, Ar, C2H6, C3H8, C2H2, HCN, CO2 Equilibrium Temperatures 2 1/4 Recall that TEQ ~ (L*/d ) Planet Distance (au) TEQ (K) Mercury 0.38 400 Venus 0.72 291 Earth 1.00 247 Mars 1.52 200 Jupiter 5.20 108 Saturn 9.53 80 Uranus 19.2 56 Neptune 30.1 45 The Atmosphere of Titan Pressure: 1.5 bars Temperature: 95 K Condensation sequence: • Jovian Moons: H2O ice • Saturnian Moons: NH3, CH4 2NH3 + sunlight è N2 + 3H2 CH4 + sunlight è CH, CH2 Implications of Methane Free CH4 requires replenishment • Liquid methane on the surface? Hazy atmosphere/clouds may suggest methane/ ethane precipitation. The freezing points of CH4 and C2H6 are 91 and 92K, respectively. (Titan has a mean temperature of 95K) (Liquid natural gas anyone?) This atmosphere may resemble the primordial terrestrial atmosphere.
    [Show full text]
  • The Gravity Field and Interior Structure of Dione
    The gravity field and interior structure of Dione Marco Zannoni1*, Douglas Hemingway2,3, Luis Gomez Casajus1, Paolo Tortora1 1Dipartimento di Ingegneria Industriale, Università di Bologna, Forlì, Italy 2Department of Earth & Planetary Science, University of California Berkeley, Berkeley, California, USA 3Department of Terrestrial Magnetism, Carnegie Institution for Science, Washington, DC, USA *Corresponding author. Abstract During its mission in the Saturn system, Cassini performed five close flybys of Dione. During three of them, radio tracking data were collected during the closest approach, allowing estimation of the full degree-2 gravity field by precise spacecraft orbit determination. 6 The gravity field of Dione is dominated by J2 and C22, for which our best estimates are J2 x 10 = 1496 ± 11 and 6 C22 x 10 = 364.8 ± 1.8 (unnormalized coefficients, 1-σ uncertainty). Their ratio is J2/C22 = 4.102 ± 0.044, showing a significative departure (about 17-σ) from the theoretical value of 10/3, predicted for a relaxed body in slow, synchronous rotation around a planet. Therefore, it is not possible to retrieve the moment of inertia directly from the measured gravitational field. The interior structure of Dione is investigated by a combined analysis of its gravity and topography, which exhibits an even larger deviation from hydrostatic equilibrium, suggesting some degree of compensation. The gravity of Dione is far from the expectation for an undifferentiated hydrostatic body, so we built a series of three-layer models, and considered both Airy and Pratt compensation mechanisms. The interpretation is non-unique, but Dione’s excess topography may suggest some degree of Airy-type isostasy, meaning that the outer ice shell is underlain by a higher density, lower viscosity layer, such as a subsurface liquid water ocean.
    [Show full text]
  • Planetary Rings
    CLBE001-ESS2E November 10, 2006 21:56 100-C 25-C 50-C 75-C C+M 50-C+M C+Y 50-C+Y M+Y 50-M+Y 100-M 25-M 50-M 75-M 100-Y 25-Y 50-Y 75-Y 100-K 25-K 25-19-19 50-K 50-40-40 75-K 75-64-64 Planetary Rings Carolyn C. Porco Space Science Institute Boulder, Colorado Douglas P. Hamilton University of Maryland College Park, Maryland CHAPTER 27 1. Introduction 5. Ring Origins 2. Sources of Information 6. Prospects for the Future 3. Overview of Ring Structure Bibliography 4. Ring Processes 1. Introduction houses, from coalescing under their own gravity into larger bodies. Rings are arranged around planets in strikingly dif- Planetary rings are those strikingly flat and circular ap- ferent ways despite the similar underlying physical pro- pendages embracing all the giant planets in the outer Solar cesses that govern them. Gravitational tugs from satellites System: Jupiter, Saturn, Uranus, and Neptune. Like their account for some of the structure of densely-packed mas- cousins, the spiral galaxies, they are formed of many bod- sive rings [see Solar System Dynamics: Regular and ies, independently orbiting in a central gravitational field. Chaotic Motion], while nongravitational effects, includ- Rings also share many characteristics with, and offer in- ing solar radiation pressure and electromagnetic forces, valuable insights into, flattened systems of gas and collid- dominate the dynamics of the fainter and more diffuse dusty ing debris that ultimately form solar systems. Ring systems rings. Spacecraft flybys of all of the giant planets and, more are accessible laboratories capable of providing clues about recently, orbiters at Jupiter and Saturn, have revolutionized processes important in these circumstellar disks, structures our understanding of planetary rings.
    [Show full text]
  • The Sources and Dynamical Mechanisms Responsible for Differing Regolith Cover on Satellites Embedded in Saturn’S E Ring
    50th Lunar and Planetary Science Conference 2019 (LPI Contrib. No. 2132) 2790.pdf WHY SO MUTED? THE SOURCES AND DYNAMICAL MECHANISMS RESPONSIBLE FOR DIFFERING REGOLITH COVER ON SATELLITES EMBEDDED IN SATURN’S E RING. S. J. Morrison1 and S. G. Zaidi1, 1Center for Exoplanets and Habitable Worlds, 525 Davey Laboratory, The Pennsylvania State Uni- versity, University Park, PA, 16802, USA ([email protected]) Introduction: Saturn’s E ring, sourced primarily by resonances with Tethys and Dione. We also numerically cryovolcanic material erupted from Enceladus, extends integrate E ring particle trajectories including these outward from Enceladus’ orbit to beyond Dione’s orbit forces using the integrator package REBOUND and RE- [1][2]. Amongst the satellites embedded in this ring, BOUNDx [10-12]. We use initial orbits for the Satur- there are observed differences in regolith cover. In par- nian System from [13] and estimated masses for the tad- ticular, the small satellites Telesto, Calypso, Helene, pole moons from [7] that assume an average density of and Polydeuces have more muted surfaces, an absence 0.6 g/cc. We include Saturn’s gravitational harmonics of small craters, and downslope transport of regolith up to J4 and plasma drag forces arising from collisions within large craters than observed on Tethys and Dione with co-rotating O+ ions, the primary constituent of on similar distance scales [3][4]. However, these small plasma in the region of the Saturnian system of interest. satellites orbit in a different dynamical environment: Results: To provide insight into whether outwardly Telesto and Calypso are on leading and trailing tadpole drifting E ring particles should accumulate in the 1:1 orbits about the L4 and L5 Lagrange points in the co- resonances with Tethys and Dione, we compare the orbital 1:1 mean motion resonance with Tethys, respec- timescale for a particle of a given size to drift across the tively, as are Helene and Polydeuces tadpoles of Dione maximum libration width of this resonance to the corre- [e.g.
    [Show full text]
  • Observing the Universe
    ObservingObserving thethe UniverseUniverse :: aa TravelTravel ThroughThrough SpaceSpace andand TimeTime Enrico Flamini Agenzia Spaziale Italiana Tokyo 2009 When you rise your head to the night sky, what your eyes are observing may be astonishing. However it is only a small portion of the electromagnetic spectrum of the Universe: the visible . But any electromagnetic signal, indipendently from its frequency, travels at the speed of light. When we observe a star or a galaxy we see the photons produced at the moment of their production, their travel could have been incredibly long: it may be lasted millions or billions of years. Looking at the sky at frequencies much higher then visible, like in the X-ray or gamma-ray energy range, we can observe the so called “violent sky” where extremely energetic fenoena occurs.like Pulsar, quasars, AGN, Supernova CosmicCosmic RaysRays:: messengersmessengers fromfrom thethe extremeextreme universeuniverse We cannot see the deep universe at E > few TeV, since photons are attenuated through →e± on the CMB + IR backgrounds. But using cosmic rays we should be able to ‘see’ up to ~ 6 x 1010 GeV before they get attenuated by other interaction. Sources Sources → Primordial origin Primordial 7 Redshift z = 0 (t = 13.7 Gyr = now ! ) Going to a frequency lower then the visible light, and cooling down the instrument nearby absolute zero, it’s possible to observe signals produced millions or billions of years ago: we may travel near the instant of the formation of our universe: 13.7 By. Redshift z = 1.4 (t = 4.7 Gyr) Credits A. Cimatti Univ. Bologna Redshift z = 5.7 (t = 1 Gyr) Credits A.
    [Show full text]
  • Long-Term Evolution and Stability of Saturnian Small Satellites
    MNRAS 000, 1–17 (2016) Preprint 30 August 2021 Compiled using MNRAS LATEX style file v3.0 Long-term Evolution and Stability of Saturnian Small Satellites: Aegaeon, Methone, Anthe, and Pallene. M. A. Mun˜oz-Guti´errez,1⋆ and S. Giuliatti Winter1 1Universidade Estadual Paulista - UNESP, Grupo de Dinˆamica Orbital e Planetologia, Av. Ariberto Pereira da Cunha, 333, Guaratinguet´a-SP, 12516-410, Brazil Accepted XXX. Received YYY; in original form ZZZ ABSTRACT Aegaeon, Methone, Anthe, and Pallene are four Saturnian small moons, discovered by the Cassini spacecraft. Although their orbital characterization has been carried on by a number of authors, their long-term evolution has not been studied in detail so far. In this work, we numerically explore the long-term evolution, up to 105 yr, of the small moons in a system formed by an oblate Saturn and the five largest moons close to the region: Janus, Epimetheus, Mimas, Enceladus, and Tethys. By using frequency analysis we determined the stability of the small moons and characterize, through diffusion maps, the dynamical behavior of a wide region of geometric phase space, a vs e, surrounding them. Those maps could shed light on the possible initial number of small bodies close to Mimas, and help to better understand the dynamical origin of the small satellites. We found that the four small moons are long-term stable and no mark of chaos is found for them. Aegaeon, Methone, and Anthe could remain unaltered for at least ∼ 0.5Myr, given the current configuration of the system. They remain well- trapped in the corotation eccentricity resonances with Mimas in which they currently librate.
    [Show full text]