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 λ=−13∘±16∘, 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.
Cite
@article{arxiv.1712.06409,
title = {Stellar Spin-Orbit Alignment for Kepler-9, a Multi-transiting Planetary system with Two Outer Planets Near 2:1 Resonance},
author = {Songhu Wang and Brett Addison and Debra A. Fischer and John M. Brewer and Howard Isaacson and Andrew W. Howard and Gregory Laughlin},
journal= {arXiv preprint arXiv:1712.06409},
year = {2018}
}
Comments
Accepted for publication in the Astronomical Journal