A Compact Spectrograph to Search for Extrasolar Planets

Abstract: The most successful method used so far to search for extrasolar planets is the radial velocity technique, where periodical shifts on the measured emission from a star provide evidence for an orbiting planet. This method has been used on large telescopes with large and expensive instrumentation, only enabling a small amount of observing time per star. We have developed a compact spectrograph fed by one or several single-mode fibres that avoids the need for complex fibre scrambling or gas absorption cells for calibration. In principle, this will enable planet searches around bright stars over the next few years. We aim to pave the way for large networks of small telescopes searching for Earth-like planets. At a resolving power of R~50000, I have characterized this spectrograph, determined its stability and the fidelity required for a simultaneous calibration source.