Closure Phase Signatures of Planet Transit Events

Planet transit events present as attractive targets for the ultrahigh-resolution capabilities afforded by optical interferometers. Herein is presented an evaluation of the possibility of detection of such events through measurement of high-precision closure phases with the MIRC instrument on the CHARA Array. Recovery of the transit position angle on the sky appears readily achievable with the existing capabilities of the instrument, along with characterization of other system parameters, such as stellar radius, planet radius, and other parameters of the transit event. This technique is the only one presently available that can provide a transiting planet's orbital plane position angle and can directly determine the planet's radius independent of any outside observations, appearing able to improve substantially upon other determinations of that radius. Additional directly observed parameters—also not dependent on transit photometry or spectroscopy—include impact parameter, transit ingress time, transit velocity, and stellar radius.