Saturn’s Mysterious Arc-embedded Moons: Recycled Fluff?
نویسندگان
چکیده
Introduction: The satellites of Saturn less than 150 km radius occupy several dynamical niches: within rings (Pan, Daphnis, Atlas, Prometheus, Pandora), Coorbiting (Janus and Epimetheus), orbiting among faint rings or in ring arcs (Aegaeon, Methone, Anthe, Pallene) [1], and populating libration regions of larger moons (Telesto, Calypso, Polydeuces, and Helene). Hyperion orbits between Titan and Iapetus, and Phoebe is in a retrograde orbit well outside the orbits of the large satellites along with many other irregular satellites. The inner satellites groups are morphologically distinct from one another. All are low density: those for which masses and sizes have been well measured [2,3], have mean densities ρ of ~430-640 kg m -3 . Cassini images of the arc-embedded moons show these are far smoother and more ovoid than other small satellites, whether of Saturn or other planets (and compared to small asteroids and comets) (Fig. 1). Methone and Pallene have been imaged well enough to use standard limb-finding and ellipsoidal solutions (54 and 14 pixels/mean radius); Aegaeon is less well measured (3 pixels/radius); fit ellipsoid shapes are given in Table 1. Methone is particularly smooth; the best images have 27 m/pixel and still show no surface or limb topography.
منابع مشابه
Gravitoelectrodynamics in Saturn’s F ring: encounters with Prometheus and Pandora
The dynamics of Saturn’s F ring have been a matter of curiosity ever since Voyagers 1 and 2 sent back pictures of the ring’s unusual features. Some of these images showed three distinct ringlets with the outer two displaying a kinked and braided appearance. Many models have been proposed to explain the braiding seen in these images; most of these invoke perturbations caused by the shepherding m...
متن کاملDensity Waves Observed by Cassini Stellar Occultations as Probes of Saturn’s
Introduction: Spiral density waves are launched in Saturn’s rings at locations of orbital resonances with nearby moons. These waves provide a means of probing fundamental properties of the ring such as mass, thickness, and collision velocities [1, 2]. These properties constrain models of the origin and evolution of Saturn’s rings. Density waves are collisionally damped, and the damping therefor...
متن کاملPhysical properties of the small moon Aegaeon (Saturn LIII)
Aegaeon (Saturn LIII) is located within an arc of debris near the inner edge of Saturn’s G ring [1], and is the currently the smallest isolated moon of Saturn known [2]. On January 27, 2010 the Cassini spacecraft flew within 15,000 km of Aegaeon, obtaining images with sufficient spatial resolution (better than 100 meters/pixel) to resolve this tiny moon. These data reveal that the moon is stron...
متن کاملDiamagnetic expulsion as a possible cause of the origin and stability of saturn’s rings
To date, the origin and evolution of Saturn’s rings have not been consistently explained. There are several hypotheses concerning the origin of Saturn’s rings, which can be summarized as follows.1 (a) The ring particles can be collision-generated debris from current moons. (b) A satellite in the Roche Zone was destroyed by a passing comet. (c) A massive comet was tidally disrupted during a clos...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2013