Terrestrial and Habitable Planet Formation in Binary and Multi-star Systems

Source: arXiv


One of the most surprising discoveries of extrasolar planets is the detection of planets in moderately close binary star systems. The Jovian-type planets in the two binaries of Gamma Cephei and GJ 86 have brought to the forefront questions on the formation of giant planets and the possibility of the existence of smaller bodies in such dynamically complex environments. The diverse dynamical characteristics of these objects have made scientists wonder to what extent the current theories of planet formation can be applied to binaries and multiple star systems. At present, the sensitivity of the detection techniques does not allow routine discovery of Earth-sized bodies in binary systems. However, with the advancement of new techniques, and with the recent launch of CoRoT and the launch of Kepler in late 2008, the detection of more planets (possibly terrestrial-class objects) in such systems is on the horizon. Theoretical studies and numerical modeling of terrestrial and habitable planet formation are, therefore, necessary to gain fundamental insights into the prospects for life in such systems and have great strategic impact on NASA science and missions. Comment: 7 pages, White Paper Submitted to the NASA/NSF ExoPlanet Task Force

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    ABSTRACT: Recent radial velocity observations have indicated that Jovian-type planets can exist in moderately close binary star systems. Numerical simulations of the dynamical stability of terrestrial-class planets in such environments have shown that, in addition to their giant planets, these systems can also harbor Earth-like objects. In this paper, we study the late stage of terrestrial planet formation in such binary-planetary systems, and present the results of the simulations of the formation of Earth-like bodies in their habitable zones. We consider a circumprimary disk of Moon- to Mars-sized objects and numerically integrate the orbits of these bodies at the presence of the Jovian-type planet of the system and for different values of the mass, semimajor axis, and orbital eccentricity of the secondary star. Results indicate that, Earth-like objects, with substantial amounts of water, can form in the habitable zone of the primary star. Simulations also indicate that, by transferring angular momentum from the secondary star to protoplanetary objects, the giant planet of the system plays a key role in the radial mixing of these bodies and the water contents of the final terrestrial planets. We will discuss the results of our simulation and show that the formation of habitable planets in binary-planetary systems is more probable in binaries with moderate to large perihelia.
    Preview · Article · Mar 2007 · The Astrophysical Journal
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    ABSTRACT: Using the results of Pichardo et al., we determine regions of dynamical stability where planets (or discs in general) could survive in stable orbits around binary stellar systems. We produce this study for 161 binary stars in the solar neighbourhood with known orbital parameters. Additionally, we constructed numerically the discs (invariant loops) around five binary systems with known orbital parameters and with confirmed planets: HIP 10138, HIP 4954, HIP 67275, HIP 116727 and Kepler 16, as a test to the approximation of Pichardo et al. In each single case, the reported position of the planets lies within our calculated stability regions. This study intends to provide a guide in the search for planets around binary systems with well-known orbital parameters, since our method defines precise limits for the stable regions, where discs may have established and planets formed.
    Full-text · Article · Aug 2012 · Monthly Notices of the Royal Astronomical Society