THE WELL-ALIGNED ORBIT OF WASP-84b: EVIDENCE FOR DISK MIGRATION OF A HOT JUPITER
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Anderson-2015-THE WELL-ALIGNED ORB.pdf
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Author(s)
Anderson, D. R.
Triaud, Amaury
Turner, O. D.
Brown, D. J. A.
Clark, B. J. M.
Smalley, B.
Cameron, A. Collier
Doyle, A. P.
Gillon, M.
Hellier, C.
Date Issued
February 2015
Journal
Astrophysical Journal
Publisher
Institute of Physics/American Astronomical Society
Citation
Anderson, D. R., A. H. M. J. Triaud, O. D. Turner, D. J. A. Brown, B. J. M. Clark, B. Smalley, A. Collier Cameron, et al. “THE WELL-ALIGNED ORBIT OF WASP-84b: EVIDENCE FOR DISK MIGRATION OF A HOT JUPITER.” The Astrophysical Journal 800, no. 1 (February 9, 2015): L9. © 2015 American Astronomical Society.
Version
Final published version
Abstract
We report the sky-projected orbital obliquity (spin–orbit angle) of WASP-84 b, a 0.69M[subscript Jup] planet in an 8.52 day orbit around a G9V/K0V star, to be λ = −0.3 ± 1.7°. We obtain a true obliquity of ψ = 17.3 ± 7.7° from a measurement of the inclination of the stellar spin axis with respect to the sky plane. Due to the young age and the weak tidal forcing of the system, we suggest that the orbit of WASP-84b is unlikely to have both realigned and circularized from the misaligned and/or eccentric orbit likely to have arisen from high-eccentricity migration. Therefore we conclude that the planet probably migrated via interaction with the protoplanetary disk. This would make it the first "hot Jupiter" (p< 10d) to have been shown to have migrated via this pathway. Further, we argue that the distribution of obliquities for planets orbiting cool stars (T[subscript eff] < 6250 K) suggests that high-eccentricity migration is an important pathway for the formation of short-orbit, giant planets.
MIT Department
Massachusetts Institute of Technology. Department of Physics
MIT Kavli Institute for Astrophysics and Space Research
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DOI of Published Version
https://doi.org/10.1088/2041-8205/800/1/l9
