Outer Planets

Titan's Ontario Lacus: Smoothness constraints from Cassini RADAR

The Cassini spacecraft has been orbiting Saturn since 2004, with frequent flybys of the largest moon Titan. With its thick atmosphere rich in nitrogen and hydrocarbons, it was once thought that Titan was covered in a global ocean of methane. Cassini optical and microwave imaging instruments have since revealed a world with a solid surface, strikingly similar in physical appearance to Earth, complete with lakes of liquid methane/ethane in the polar regions.

The Rings of Saturn as seen by Cassini CIRS

 An extensive set of thermal measurements of Saturn’s main rings has been returned by the Cassini Composite Infrared spectrometer (CIRS) over the past five years at a variety of ring geometries that are not observable from Earth. The largest temperature changes on the lit face of the rings are driven by variations in phase angle, including an unexpected thermal surge at low phase angles. Temperatures at equinox were retrieved for the first time, as the sun traversed from the south to north side of the rings in mid-August.

Weathering on Icy Satellites: Probing the Near Surface Using Infrared Spectroscopy

Infrared spectra of icy satellites contain information about the surface composition and the phase state of those materials.  For example, the phase of H2O-ice can be used to interpret the temperature and radiation history of an icy surface.  Optical constants derived from laboratory data are needed to create model spectra for comparison to observations and may lead to a new understanding of surface processes.

Formation and Detectability of Planets around Alpha Cen B

We simulate the formation of planetary systems around Alpha Centauri B. The N-body accretionary evolution of a 1/r disk populated with 400-900 lunar-mass oligarchs is followed for 200 Myr. All simulations lead to the formation of multiple-planet systems with at least one planet in the 1-2 Msun mass range at 0.5-1.5 AU. We examine the detectability of our simulated planetary systems by generating synthetic radial velocity observations including noise based on the radial velocity residuals to the recently published three planet fit to the nearby K0V star HD 69830.

Geodynamics of Icy Satellites

There are at least 37 objects in this solar system with masses greater than 1020 kg, two thirds of which have surfaces made primarily of water ice. The handful of icy bodies studied by spacecraft have revealed an enormous diversity of bizarre and unanticipated features, from geysers on Triton and Enceladus, to the peculiar shapes of Iapetus and 2003 EL61. I will discuss three aspects of icy body geodynamics: using surface observations to constrain their thermal evolution; the role of tidal heating; and their potential to undergo reorientation. 

Icy Bodies of the Outer Solar System: What Does The Spectroscopy Tell Us?

Spectroscopy, particularly in the near-infrared, continues to be the most effective means for determining the compositions of the surfaces of planetary bodies. Planetary spectroscopy has moved beyond the mere identification of species to the quantitative interpretation of mixtures of several materials and the physical states in which they occur. Dr.

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