Detection of extra-solar planets with the Keck Interferometer

We discuss the development of the "Differential Phase" detection technique for the Keck Interferometer "Hot Jupiter" Key Science Program. The goal of the "Hot Jupiter" Key Science Program is the direct detection and infrared; low-resolution spectroscopic characterization of previously detected, T >= 1000 K extra-solar planets. Although many extra solar planets are sufficiently bright to detect with large telescopes, the proximity of these planets to the much brighter stellar primary makes direct detection difficult because of angular resolution and intensity dynamic range limitations. The Keck Interferometer. working in the near infrared, has sufficient angular resolution and sensitivity to detect some of the currently known extra solar planets; however, the intensity dynamic range required (1:30,000) is substantially beyond the capability of the traditional techniques of optical and infrared direct-detection interferometers.