Closure Phase Signatures of Planet Transit Events

TL;DR

This paper evaluates the use of optical interferometry with the MIRC instrument to detect and characterize exoplanet transits through closure phase measurements, enabling direct determination of orbital and physical parameters.

Contribution

It demonstrates that high-precision closure phase measurements can detect transit parameters and directly measure the planet's radius and orbital plane, surpassing traditional methods.

Findings

Transit position angle can be recovered with current capabilities.

Planet and stellar radii can be directly measured.

Additional parameters like impact parameter and transit velocity are obtainable.

Abstract

Planet transit events present as attractive targets for the ultra-high-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 upon 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 upon transit photometry or spectroscopy - include impact parameter, transit ingress time, transit velocity and stellar radius.