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THE DEBRIS DISK AROUND HR 8799

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      Most cited references 62

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      Validation of the new Hipparcos reduction

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        Origin of the cataclysmic Late Heavy Bombardment period of the terrestrial planets.

        The petrology record on the Moon suggests that a cataclysmic spike in the cratering rate occurred approximately 700 million years after the planets formed; this event is known as the Late Heavy Bombardment (LHB). Planetary formation theories cannot naturally account for an intense period of planetesimal bombardment so late in Solar System history. Several models have been proposed to explain a late impact spike, but none of them has been set within a self-consistent framework of Solar System evolution. Here we propose that the LHB was triggered by the rapid migration of the giant planets, which occurred after a long quiescent period. During this burst of migration, the planetesimal disk outside the orbits of the planets was destabilized, causing a sudden massive delivery of planetesimals to the inner Solar System. The asteroid belt was also strongly perturbed, with these objects supplying a significant fraction of the LHB impactors in accordance with recent geochemical evidence. Our model not only naturally explains the LHB, but also reproduces the observational constraints of the outer Solar System.
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          Direct imaging of multiple planets orbiting the star HR 8799.

          Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step toward imaging Earth-like planets. Imaging detections are challenging because of the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our solar system.
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            Author and article information

            Journal
            The Astrophysical Journal
            ApJ
            IOP Publishing
            0004-637X
            1538-4357
            November 01 2009
            November 01 2009
            October 09 2009
            : 705
            : 1
            : 314-327
            10.1088/0004-637X/705/1/314
            © 2009

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