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arXiv · 1108.4493

Further Observations of the Tilted Planet XO-3: A New Determination of Spin-Orbit Misalignment, and Limits on Differential Rotation

Teruyuki Hirano·Norio Narita·Bun'ei Sato·Joshua N. Winn·Wako Aoki·Motohide Tamura·Atsushi Taruya·Yasushi Suto
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Abstract

We report on observations of the Rossiter-McLaughlin (RM) effect for the XO-3 exoplanetary system. The RM effect for the system was previously measured by two different groups, but their results were statistically inconsistent. To obtain a decisive result we observed two full transits of XO-3b with the Subaru 8.2-m telescope. By modeling these data with a new and more accurate analytic formula for the RM effect, we find the projected spin-orbit angle to be λ=37.3 deg \pm 3.0 deg, in good agreement with the previous finding by Winn et al. (2009). In addition, an offset of ~22 m/s was observed between the two transit datasets. This offset could be a signal of a third body in the XO-3 system, a possibility that should be checked with future observations. We also attempt to search for a possible signature of the stellar differential rotation in the RM data for the first time, and put weak upper limits on the differential rotation parameters.

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Teruyuki Hirano, Norio Narita, Bun'ei Sato, Joshua N. Winn, Wako Aoki, Motohide Tamura, Atsushi Taruya, Yasushi Suto. 2011-10-05. Further Observations of the Tilted Planet XO-3: A New Determination of Spin-Orbit Misalignment, and Limits on Differential Rotation. https://doi.org/10.1093/pasj%2F63.6.l57

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