Orbital Orientations of Exoplanets: Hat-p-4b is Prograde and Hat-p-14b is Retrograde
Author(s)Winn, Joshua Nathan; Howard, Andrew W.; Johnson, John Asher; Marcy, Geoffrey W.; Isaacson, Howard; Shporer, Avi; Bakos, Gaspar A.; Hartman, Joel D.; Holman, Matthew J.; Albrecht, Simon H.; Crepp, Justin R.; Morton, Timothy D.; ... Show more Show less
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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 λ = –4.9 ± 11.9 deg. In contrast, HAT-P-14b is retrograde, with λ = 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.
DepartmentKavli Institute for Astrophysics and Space Research; Massachusetts Institute of Technology. Department of Physics
Winn, Joshua N. et al. “ORBITAL ORIENTATIONS OF EXOPLANETS: HAT-P-4b IS PROGRADE AND HAT-P-14b IS RETROGRADE.” The Astronomical Journal 141.2 (2011): 63.
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