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Project Progress

Despite many observational techniques that are currently used in detecting extrasolar planets, the problems associated with the detection of terrestrial-sized objects are still unresolved. The residual effects, due to a possible terrestrial-class planet in an extrasolar planetary system, are so small that they fall outside the range of the sensitivity of most detection techniques. In many cases, the dynamical characteristics of an extrasolar planetary system, or its unexpected assembly of bodies (e.g., hot Jupiters around single stars, or Jupiter-like planets in dual- and triple-star systems) have made the matter more complicated. For instance, in a system where a star is host to a close-in Jovian-type planet, the strong perturbations from the planetary companion cause the residual effects of a possible terrestrial planet to have so much uncertainty that they become unreliable. In collaboration with E. Agol from the Astrobiology team of the University of Washington in Seattle, Haghighipour has initiated a new project that aims to overcome this difficulty by measuring the transit time of an extrasolar planet and analyzing its variations due to the presence of another planetary object. Using variations in the periodicity of the time of the transit of a giant planet in a single-planet extrasolar planetary system, the TTV (Transit Timing Variation) method is capable of identifying an additional planet, and also constraining its mass and orbital elements. In general, TTV is capable of constraining the mass of a planetary companion approximately one order of magnitude smaller than those detected by a 5 m/s precision radial velocity technique. Haghighipour is currently involved in studying the dynamics of terrestrial planets in resonant orbits in system with hot-Jupiters to determine the variation in their transit timing due to perturbations from the giant body.