Measurement of the nodal precession of WASP-33 b via doppler tomography
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We have analyzed new and archival time series spectra taken six years apart during transits of the hot Jupiter WASP-33 b, and spectroscopically resolved the line profile perturbation caused by the Rossiter–McLaughlin effect. The motion of this line profile perturbation is determined by the path of the planet across the stellar disk, which we show to have changed between the two epochs due to nodal precession of the planetary orbit. We measured rates of change of the impact parameter and the sky-projected spin–orbit misalignment of db/dt = -0.0228+0.0050-0.0018 yr-1 and dλ/dt = -0º.373+0.089-0.076 yr-1, respectively, corresponding to a rate of nodal precession of dΩ/dt =-0º.373+0.031-0.083 yr-1. This is only the second measurement of nodal precession for a confirmed exoplanet transiting a single star. Finally, we used the rate of precession to set limits on the stellar gravitational quadrupole moment of 0.0054≤ J2 ≤ 0.035.
Johnson , M C , Cochran , W D , Cameron , A C & Bayliss , D 2015 , ' Measurement of the nodal precession of WASP-33 b via doppler tomography ' Astrophysical Journal Letters , vol. 810 , no. 2 . DOI: 10.1088/2041-8205/810/2/L23
Astrophysical Journal Letters
© 2015. The American Astronomical Society. All rights reserved. This work is made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at http://dx.doi.org/10.1088/2041-8205/810/2/L23
DescriptionM.C.J. is supported by a NASA Earth and Space Science Fellowship under Grant NNX12AL59H. This work was also supported by NASA Origins of Solar Systems Program grant NNX11AC34G to W.D.C.
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