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A determination of the spin-orbit alignment of the anomalously dense planet orbiting HD 149026

Wolf, Aaron S. and Laughlin, Gregory and Henry, Gregory W. and Fischer, Debra A. and Marcy, Geoffrey W. and Butler, Paul and Vogt, Steve (2007) A determination of the spin-orbit alignment of the anomalously dense planet orbiting HD 149026. Astrophysical Journal, 667 (1). pp. 549-556. ISSN 0004-637X.

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We report 35 radial velocity measurements of HD 149026 taken with the Keck Telescope. Of these measurements, 15 were made during the transit of the companion planet HD 149026b, which occurred on 2005 June 25. These velocities provide a high-cadence observation of the Rossiter-McLaughlin effect, the shifting of photospheric line profiles that occurs when a planet occults a portion of the rotating stellar surface. We combine these radial velocities with previously published radial velocity and photometric data sets and derive a composite best-fit model for the star-planet system. This model confirms and improves previously published orbital parameters, including the remarkably small planetary radius, the planetary mass, and the orbital inclination, found to be Rp/RJup = 0.718 ± 0.065, Mp/MJup = 0.352 ± 0.025, and I = 86.1° ± 1.4°, respectively. Together the planetary mass and radius determinations imply a mean planetary density of 1.18(-0.30)(+0.38)g cm(-3). The new data also allow for the determination of the angle between the apparent stellar equator and the orbital plane, which we constrain to be λ = -12° ± 15°.

Item Type:Article
Related URLs:
URLURL TypeDescription
Laughlin, Gregory0000-0002-3253-2621
Henry, Gregory W.0000-0003-4155-8513
Fischer, Debra A.0000-0003-2221-0861
Marcy, Geoffrey W.0000-0002-2909-0113
Additional Information:© 2007. The American Astronomical Society. Received 2005 November 1; accepted 2006 February 11. We thank Peter Bodenheimer, David Charbonneau, and Josh Winn for useful discussions. Aaron Wolf’s research on this project was supported by the NASA Astrobiology Institute through grant NNA 04-CC99A (to G.L.). This research was also supported by NASA grant NNG 04-GK19G and NSF grant AST 04-49986 (to G.L.); NASA grant NNG 05-G164G (to D.A.F.); NASA grant NCC 5-511 and NSF grant HRD 97-06268 (to G.W.H.); NSF grant AST 03-07493 (to S.S.V.); NSF grant AST 99-88087 and travel support from the Carnegie Institution of Washington (to R.P.B.); NASA grant NAG5-8299 and NSF grant AST 95-20443 (to G.W.M.); and by Sun Microsystems. This research has made use of the Simbad database, operated at CDS, Strasbourg, France. Finally, the authors wish to extend thanks to those of Hawaiian ancestry on whose sacred mountain of Mauna Kea we are privileged to be guests. Without their generous hospitality, the Keck observations presented herein would not have been possible.
Funding AgencyGrant Number
NSFAST 04-49986
NSFHRD 97-06268
NSFAST 03-07493
NSFAST 99-88087
Carnegie Institute of WashingtonUNSPECIFIED
NASANAG 5-8299
NSFAST 95-20443
Sun MicrosystemsUNSPECIFIED
Subject Keywords:planetary systems—planets and satellites: general—stars: individual (HD 149026)
Issue or Number:1
Record Number:CaltechAUTHORS:WOLapj07
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:12647
Deposited By: Jason Perez
Deposited On:14 Jan 2009 22:58
Last Modified:09 Mar 2020 13:18

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