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Project Progress

Short-period terrestrial-mass objects are predicted to be captured into near mean-motion resonant orbits with migrating giant planets. These objects are potentially detectable via transit photometry of their host stars, or the measurement of the variations of the transit-timing due to their Jovian-mass planetary companions. The detectability of these objects requires their long-term stability implying that to determine the prospects of their detection, it is necessary to develop a detailed understanding of the interactions between close-in terrestrial and Jovian planets, and the region of their parameter-space for which a terrestrial-class object will be dynamically stable. We have carried out extensive numerical simulations of the dynamical evolution of a short-period Earth-like object in the vicinity of a close-in giant planet, and have identified the ranges of its orbital parameters for which the system is stable. Our results indicate that for a tidally locked Jovian body, a terrestrial-class object can be stable on low eccentricity (< 0.2) and low inclination (< 15 deg.) orbits (Figure 1).

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We have also been able to identify regions where a terrestrial planet can be in stable 1:2 or 1:3 mean-motion resonances with the giant planet. As shown in Figure 2, the synthetic transit timing variations of a giant planet in such systems have large amplitudes. Our simulations also indiate that regions may exist in the vicinity of unstable mean-motion resonances, where a super-Earth object can maintain its orbit for a long time and produce strong signals detectable by the transit-timing variations method (Figure 2).

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