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Published September 20, 2012 | Published + Submitted
Journal Article Open

Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments

Abstract

We provide evidence that the obliquities of stars with close-in giant planets were initially nearly random, and that the low obliquities that are often observed are a consequence of star-planet tidal interactions. The evidence is based on 14 new measurements of the Rossiter-McLaughlin effect (for the systems HAT-P-6, HAT-P-7, HAT-P-16, HAT-P-24, HAT-P-32, HAT-P-34, WASP-12, WASP-16, WASP-18, WASP-19, WASP-26, WASP-31, Gl 436, and Kepler-8), as well as a critical review of previous observations. The low-obliquity (well-aligned) systems are those for which the expected tidal timescale is short, and likewise the high-obliquity (misaligned and retrograde) systems are those for which the expected timescale is long. At face value, this finding indicates that the origin of hot Jupiters involves dynamical interactions like planet-planet interactions or the Kozai effect that tilt their orbits rather than inspiraling due to interaction with a protoplanetary disk. We discuss the status of this hypothesis and the observations that are needed for a more definitive conclusion.

Additional Information

© 2012 The American Astronomical Society. Received 2012 April 19; accepted 2012 July 18; published 2012 August 30. The data presented herein were collected with the Magellan (Clay) Telescope located at Las Campanas Observatory, Chile, and the Keck I telescope at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The authors are grateful to Nevin Weinberg, Dan Fabrycky, Smadar Naoz, Amaury Triaud, and René Heller for comments on the manuscript. Work by S.A. and J.N.W. was supported by NASA Origins award NNX09AB33G and NSF grant No. 1108595. G.B. and J.H. acknowledge the support from grants NSF AST-1108686 and NASA NNX09AB29G. T.H. is supported by Japan Society for Promotion of Science (JSPS) Fellowship for Research (DC1: 22-5935). This research has made use of the following web resources: simbad.u-strasbg.fr, adswww.harvard.edu, arxiv.org. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W. M. Keck Foundation. We extend special thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests.

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Published - Albrecht_2012_ApJ_757_18.pdf

Submitted - 1206.6105.pdf

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Created:
August 19, 2023
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October 26, 2023