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M. Noble, Z.E. Musielak, M. Cuntz (Uni. Texas, Arlington)
Long-term orbital stability of Earth-like planets in stellar habitable zones (HZs) is necessary for the evolution of any form of life. It is then interesting to ask whether Earth-like planets can exist in stable orbits around single stars with giant planets and in multiple stellar systems? The main conclusion from previous studies is that orbits of terrestrial planets in the HZs of 70~Vir, \rho~CrB and 47~UMa are stable over the length of time required for the biological evolution, however, no long-term stability was found for Gl~876 and \upsilon~And. We have investigated orbital stability of terrestrial planets inside the HZs of three stellar systems, 51~Peg, 47~UMa and HD~210277, with known giant planets. The chosen systems have similar HZs, however, their planets have significantly different masses and orbital parameters. It is shown that stable orbits of terrestrial planets exist in the entire HZ of 51~Peg and in the inner part of the HZ of 47~UMa, but no stable orbits are found in the HZ of HD~210277. In addition, we have studied stability of orbits of Earth-like planets in one binary system (\zeta~Her) and in one triple system (\xi UMa). The obtained results allow us to draw general conclusions on the existence of stable orbits in the HZs of newly detected extra-solar planetary systems.
This work was supported by NSF, NATO and The Alexander von Humboldt Foundation.