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arXiv · 1712.06409

Stellar Spin-Orbit Alignment for Kepler-9, a Multi-transiting Planetary system with Two Outer Planets Near 2:1 Resonance

Songhu Wang·Brett Addison·Debra A. Fischer·John M. Brewer·Howard Isaacson·Andrew W. Howard·Gregory Laughlin
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Abstract

We present spectroscopic measurements of the Rossiter-McLaughlin effect for the planet b of Kepler-9 multi-transiting planet system. The resulting sky-projected spin-orbit angle is $\lambda=-13^{\circ} \pm 16^{\circ}$, which favors an aligned system and strongly disfavors highly misaligned, polar, and retrograde orbits. Including Kepler-9, there are now a total of 4 Rossiter-McLaughlin effect measurements for multiplanet systems, all of which are consistent with spin-orbit alignment.

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Songhu Wang, Brett Addison, Debra A. Fischer, John M. Brewer, Howard Isaacson, Andrew W. Howard, Gregory Laughlin. 2017-12-18. Stellar Spin-Orbit Alignment for Kepler-9, a Multi-transiting Planetary system with Two Outer Planets Near 2:1 Resonance. https://doi.org/10.3847/1538-3881/aaa2fb

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