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  • Orbital Orientations of Exo...
    Winn, Joshua N; Howard, Andrew W; Johnson, John Asher; Marcy, Geoffrey W; Isaacson, Howard; Shporer, Avi; Bakos, Gáspár Á; Hartman, Joel D; Holman, Matthew J; Albrecht, Simon; Crepp, Justin R; Morton, Timothy D

    The Astronomical journal, 02/2011, Letnik: 141, Številka: 2
    Journal Article

    We present observations of the Rossiter-McLaughlin effect for two exoplanetary systems, revealing the orientations of their orbits relative to the rotation axes of their parent stars. HAT-P-4b is prograde, with a sky-projected spin-orbit angle of Delta *l = --4.9 ? 11.9 deg. In contrast, HAT-P-14b is retrograde, with Delta *l = 189.1 ? 5.1 deg. These results conform with a previously noted pattern among the stellar hosts of close-in giant planets: hotter stars have a wide range of obliquities and cooler stars have low obliquities. This, in turn, suggests that three-body dynamics and tidal dissipation are responsible for the short-period orbits of many exoplanets. In addition, our data revealed a third body in the HAT-P-4 system, which could be a second planet or a companion star.