Published in The Astrophysical Journal
We revisit the equation for viscous damping of density waves derived from linearized theory. We show that in addition to the coefficient of shear viscosity itself the dependence of this coefficient on the rings surface mass density appears, as well as the coefficient of bulk viscosity. This was noted more than thirty years ago by Goldreich and Tre...
Published in American Astronomical Society, DDA meeting
The "propeller" moons within Saturn's rings are the first objects ever to have their orbits tracked while embedded in a disk, rather than moving through empty space (Tiscareno et al. 2010, ApJL). The km-sized "giant propellers" whose orbits have been tracked in the outer-A ring, as well as their smaller 0.1-km-sized brethren swarming in the mid-A r...
Published in American Astronomical Society, DDA meeting
We present a catalog of detected wisps , small protrusions of material (0.5 to 2 km) into the Keeler Gap of Saturn s rings from the gap s outer edge. Wisps are characterized by a sharp trailing edge followed by a slow gradation back into the edge on the leading side, typically extending between 0.1 and 1 degree of longitude (240 to 2400 km). Fewer ...
Published in Publications of the Astronomical Society of the Pacific
The James Webb Space Telescope (JWST) will enable a wealth of new scientific investigations in the near-and mid-infrared, with sensitivity and spatial/spectral resolution greatly surpassing its predecessors. In this paper, we focus upon Solar System science facilitated by JWST, discussing the most current information available concerning JWST instr...
Published in Publications of the Astronomical Society of the Pacific
The James Webb Space Telescope (JWST) will provide unprecedented opportunities to observe the rings and small satellites in our Solar System, accomplishing three primary objectives:(1) discovering new rings and moons,(2) unprecedented spectroscopy, and (3) time-domain observations. We give details on these science objectives and describe requiremen...
Published in Icarus
Several planetary satellites apparently have subsurface seas that are of great interest for, among other reasons, their possible habitability. The geologically diverse saturnian satellite Enceladus vigorously vents liquid water and vapor from fractures within a south polar depression and thus must have a liquid reservoir or active melting. However,...
Published in Icarus
We have carried out a comprehensive survey of the best Cassini ISS data of Saturn s main rings for the purpose of cataloguing all observed spiral density waves, spiral bending waves, and other radial and quasi-radial ring structure. Our survey has revealed a number of new features, including the first known resonant waves raised by Enceladus and Hy...
Published in Icarus
We present a study of the behavior of Saturn s A ring outer edge, using images and occultation data obtained by the Cassini spacecraft over a period of 8 years from 2006 to 2014. More than 5000 images and 170 occultations of the A ring outer edge are analyzed. Our fits confirm the expected response to the Janus 7: 6 Inner Lindblad resonance (ILR) b...
Published in AGU Fall Meeting Abstracts
The outer part of Saturn s A ring contains five sharp edges: the inner and outer edges of the Encke Gap and of the Keeler Gap (which contain the moons Pan and Daphnis, respectively), and the outer edge of the A ring itself. Four of these five edges are characterized by structure at moderate to high spatial frequencies, with amplitudes ranging from ...
Published in Monthly Notices of the Royal Astronomical Society
This work shows the dynamical instability that can happen to close-in satellites when planet oblateness is not accounted for in non-coplanar multiplanet systems. Simulations include two secularly interacting Jupiter-mass planets mutually inclined by 10, with the host planet either oblate or spherical. With a spherical host planet, moons within a cr...
Published in ScienceOpen Astronomy & Astrophysics
Aims. Generally, the oblateness of a planet or moon is what causes rings to settle into its equatorial plane. However, the recent suggestion that a ring system might exist (or have existed) about Rhea, a moon whose shape includes a strong prolate component pointed toward Saturn, raises the question of whether rings around a triaxial primary can be ...
Published in American Astronomical Society, AAS Meeting
In 2009, Cassini captured images of Saturn s rings during equinox, when the Sun s rays strike the ring nearly edge-on. These data provide a rare opportunity to study the vertical nature of structures such as bending waves. In the equinox images, the Mimas 5: 3 bending wave (BW) was observed to exhibit quite different brightness profiles for the two...
Published in Planetary and Space Science
Remote sensing observations meet some limitations when used to study the bulk atmospheric composition of the giant planets of our solar system. A remarkable example of the superiority of in situ probe measurements is illustrated by the exploration of Jupiter, where key measurements such as the determination of the noble gases׳ abundances and the pr...
Published in AGU Fall Meeting Abstracts
Enceladus interior structure [1] plays a critical role in understanding the composition and activity of the satellite s south polar geysers [2,3] and in interpreting its tectonic activity. Enceladus physical rotational libration, a periodic wobble superposed upon its synchronous rotation and driven by the torques resulting from the satellite s sl...
Published in American Astronomical Society, DPS meeting
Linblad resonances with Saturn’s satellites are located at many radii in the rings. While some cause density or bending waves, others hold gap edges from spreading, like the 2:1 resonance with Mimas located at the B-ring edge, the 7:6 resonance with Janus at the A-ring edge, and the 32:31 resonance with Prometheus at the inner edge of the Keeler ga...
Published in American Astronomical Society, DPS meeting
With its anticipated launch date in October 2018, the James Webb Space Telescope will tremendously advance astronomy in the near- and mid-infrared, offering sensitivity and spatial/spectral resolution greatly surpassing its predecessors. We have developed a white paper that explores observations of Solar System targets with JWST, with the goals of ...
Published in American Astronomical Society, DPS meeting
The unprecedented sensitivity and angular resolution of the James Webb Space Telescope (JWST) will make it NASA s premier space-based facility for infrared astronomy. This 6.5-meter telescope, which is optimized for observations in the near and mid infrared, will be equipped with four state-of-the-art instruments that include imaging, spectroscopy,...
Published in American Astronomical Society, DPS meeting
Every four years, Janus and Epimetheus change their orbits, because of their unique dynamical capture in horseshoe orbits (Yoder et al, 1983). Both Janus and Epimetheus drive strong density waves in the rings, but because of their configuration with variable orbits, their nearby resonance locations change every four years. As a result, the observed...
Published in American Astronomical Society, DDA meeting
We have carried out a comprehensive survey of the best Cassini ISS data of Saturn s main rings for the purpose of cataloguing all observed spiral density waves, spiral bending waves, and other radial and quasi-radial ring structure. Our survey has revealed a number of new features, including the first known resonant waves raised by Enceladus and Hy...
The James Webb Space Telescope (JWST) will be the largest and most advanced telescope ever launched into space. Due to begin operations in 2018, it will succeed the Hubble Space Telescope as humanity's premier eye on the sky. In addition to hunting for Earth-like planets around other stars, probing the early products of the Big Bang, and investigat...
