Wednesday, October 25, 2017

Spin–Orbit Misalignments of Three Jovian Planets via Doppler Tomography

Spin–Orbit Misalignments of Three Jovian Planets via Doppler Tomography


Johnson et al

We present measurements of the spin–orbit misalignments of the hot Jupiters HAT-P-41 b and WASP-79 b, and the aligned warm Jupiter Kepler-448 b. We obtain these measurements with Doppler tomography, where we spectroscopically resolve the line profile perturbation during the transit due to the Rossiter–McLaughlin effect. We analyze time series spectra obtained during portions of five transits of HAT-P-41 b, and find a value of the spin–orbit misalignment of $\lambda =-{22.1}_{-6.0}^{{+0.8}^{^\circ }}$. We reanalyze the radial velocity Rossiter–McLaughlin data on WASP-79 b obtained by Addison et al. using Doppler tomographic methodology. We measure $\lambda =-{99.1}_{-3.9}^{{+4.1}^{^\circ }}$, consistent with but more precise than the value found by Addison et al. For Kepler-448 b we perform a joint fit to the Kepler light curve, Doppler tomographic data, and a radial velocity data set from Lillo-Box et al. We find an approximately aligned orbit ($\lambda =-{7.1}_{-2.8}^{{+4.2}^{^\circ }}$), in agreement with the value found by Bourrier et al. Through analysis of the Kepler light curve we measure a stellar rotation period of ${P}_{\mathrm{rot}}=1.27\pm 0.11$ days, and use this to argue that the full three-dimensional spin–orbit misalignment is small, $\psi \sim 0^\circ $.

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