SPIN-ORBIT ALIGNMENT FOR 110 DAY PERIOD KOI368.01 FROM GRAVITY DARKENING

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 [lambda] = 10[degrees] + or - 2[degrees], a stellar obliquity of [psi] = 3[degrees]+ or -7[degrees], and a true spin-orbit alignment of [phi] = 11[degrees]+ or -3[degrees]. Although our measurement differs significantly from zero, the low value for [phi] is consistent with spin-orbit alignment. We also measure various transit parameters of the KOI-368 system: R sub(KOI-368) = 2.28 + or - 0.02 R sub([middot in circle]), R sub(p) = 1.83 + or - 0.02 R sub(jup), and i = 89[degrees].221 + or - 0[degrees].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.