Program: GN-2018B-Q-237

Since the orbit of a planet tends to lie perpendicular to the rotation axis of the host star, one way to optimize searches for planetary transits is by targeting objects with a favorable geometry, i.e., those seen at their equator. Furthermore, a low host-star luminosity and a tight habitable zone offer the highest probability of detecting transits of Earth-like planets. We propose high-dispersion near-infrared spectroscopy to measure the projected rotational velocities and spin axis orientations of seven M, L, and T ultra-cool dwarfs with accurately known photometric periods. Given degenerate equations of state, brown dwarfs attain nearly constant 0.8-1.0 Jupiter radii at ages older than 500 Myr. Rotation period and vsini measurements thus reveal the viewing geometry. Assuming spin-orbit alignment between the host ultra-cool dwarf and any surrounding planetary system, ultra-cool dwarfs viewed equator-on are excellent targets for the detection of rocky transiting planets.