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Planetary Science

J. R. Matese, A. Petculescu

John Matese's research interests concern astrophysical dynamics of dwarf planets and how the Oort Cloud interacts with the Milky Way. Of particular interest is the mechanism underlying a possible discrepancy between observed cometary orbital characteristics and in-situ distributions. A proposed explanation for the discrepancies points the effects of the tidal torque created by the galactic disk on the Oort Cloud comets. The results of the study are available here. Another intriguing aspect arises from the possibility of a substellar companion for the Sun in the Oort Cloud. By examining the scatter of Oort Cloud comets' aphelia directions, one notes an anomalous concentration along a circle passing near the galactic poles. This could point to a solar companion contributing to the galactic tide, of mass between one and four Jupiter masses and a mean distance between 10 kAU and 30 kAU.

Andi Petculescu is developing models to predict the properties of wave motion in terrestrial atmospheres (Mars, Venus, and Titan). Recent missions such as Cassini-Huygens, Mars Phoenix, and Venus Express have shown the growing interest in detecting and analyzing signatures of wave motion in planetary atmospheres. The different projects combine data analysis, theoretical and computational modeling to predict the characteristics of acoustic and gravity wave propagation in terrestrial atmospheres. A comparative analysis of the atmospheric acoustics of Earth, Mars, Venus, and Titan can be found here. These studies are important in planetary science because they guide instrumentation development and data analysis. We have recently completed a study of the generation and propagation of thunder on Titan. The results, published here, show the optimum frequency bands in which future detectors should look. Limiting the working bandwidth helps save onboard power and optimize the measurement process.