CODEX: An Ultra-stable High Resolution Spectrograph for the E-ELT

The Messenger 140 – June 2010 A high Strehl ratio imager at the E-ELT will be capable of directly detecting some of the more massive planets discovered by CODEX. The combination of these instruments will provide the E-ELT community with a full characterisation of the planetary orbits as well as atmospheres, true masses and temperature. CODEX will also follow up Earth-sized exoplanet candidates discovered by space missions and ground-based transit searches. Confirmation of the planetary origin of the photometric transit and accurate measurements of the mass of the transiting body require a radial velocity (RV) precision of a few cms–1, which CODEX will provide. Gaia will provide accurate physical stellar parameters enabling the positions of stars in the Hertzsprung– Russell diagram to be compared with those derived by CODEX from nucleochronometry and asteroseismology. Also high-redshift molecular rotational absorption lines discovered by ALMA and H i 21 cm absorption detected by SKA can be compared to optical metal lines observed with CODEX to constrain various combinations of constants involving the fine structure constant (α), the proton-to-electron mass ratio (μ) and the proton g-factor.