Abstract

The Doppler radial velocity (RV) method continues to inform our understanding of extrasolar planet formation and evolution, orbital architectures, masses, and composition. Although much progress has been made in generating precise RV time series, basic physics considerations related to the way that spectrographs are designed and built can limit the utility of Doppler observations much below one meter per second precision. As a result, effects involving stability, image quality and spectral resolution, and consequently the handling of stellar activity, currently preclude the study of Earth-mass analogues orbiting Sun-like stars. In this talk, I will describe a new type of spectrograph that uses “extreme” adaptive optics to inject starlight directly into single mode fibers. By correcting for the image-blurring effects introduced by Earth’s turbulent atmosphere, I will argue that a diffraction-limited instrument should be capable of generating unprecedented RV precision. We are constructing the first-such spectrograph of this kind for the Large Binocular Telescope in Arizona. The instrument, named “iLocater,” will benefit from input images that achieve 20 times higher spatial resolution than seeing-limited designs, enabling high spatial resolution (40 mas) and high spectral resolution (R=200,000) observations using an ultra-stable, compact optical design at low cost.