KOI-2138.01 is a transiting super-Earth planet candidate in orbit around a rapidly rotating host star that has 2.29 times the radius and 2.34 times the mass of the Sun. The star's rapid rotation spins it into an oblate spheroid with a gravity darkened equator. Observing the way KOI-2138.01 transits its host star and how it passes in front of the gravity darkened equator allows the planet's orbital inclination to be determined. KOI-2138.01 is found to have a relatively flat orbit with a projected spin-orbit alignment of only 1 ± 13 degrees. The close proximity of KOI-2138.01 from its host star also gives it an estimated dayside temperature of up to ~1300 K.
Barnes et al. (2016), "Probable Spin-Orbit Aligned Super-Earth Planet Candidate KOI-2138.01", arXiv:1512.03855 [astro-ph.EP]