Abstract
We fit the Kepler photometric light curve of the KOI-368 system using an oblate, gravity-darkened stellar model in order to constrain its spin–orbit alignment. We find that the system is relatively well-aligned with a sky-projected spin–orbit alignment of λ = 10° ± 2°, a stellar obliquity of ψ = 3° ± 7°, and a true spin–orbit alignment of φ = 11° ± 3°. Although our measurement differs significantly from zero, the low value for φ is consistent with spin–orbit alignment. We also measure various transit parameters of the KOI-368 system: RKOI-368 = 2.28 ± 0.02 R☉, Rp = 1.83 ± 0.02 Rjup, and i = 89.°221 ± 0.°013. This work shows that our gravity-darkened model can constrain long-period, well-aligned planets and M-class stars orbiting fast-rotators, allowing for measurement of a new subcategory of transiting bodies.