Precision Radial Velocity Spectrograph

Abstract

We present a conceptual design for a Precision Radial Velocity Spectrograph (PRVS) for the Gemini telescope. PRVS is a fibre fed high resolving power (R similar to 70,000 at 2.5 pixel sampling) cryogenic echelle spectrograph operating in the near infrared (0.95 - 1.8 microns) and is designed to provide 1 m/s radial velocity measurements. We identify the various error sources to overcome in order to the required stability. We have constructed models simulating likely candidates and demonstrated the ability to recover exoplanetary RV signals in the infrared. PRVS should achieve a total RV error of around 1 m/s on a typical M6V star. We use these results as an input to a simulated 5-year survey of nearby M stars. Based on a scaling of optical results, such a survey has the sensitivity to detect several terrestrial mass planets in the habitable zone around nearby stars. PRVS will thus test theoretical planet formation models, which predict an abundance of terrestrial-mass planets around low-mass stars.We have conducted limited experiments with a brass-board instrument on the Sun in the infrared to explore real-world issues achieving better than 10 m/s precision in single 10 s exposures and better than 5 m/s when integrated across a minute of observing.