Improving Earth-like planets' detection with an ELT: the differential radial velocity experiment
LESIA, Observatoire de Paris-Meudon, 5 place J. Janssen, 92195 Meudon, France e-mail: firstname.lastname@example.org
2 Université de Liège, 17 Allée du 6 Août, 4000 Sart Tilman, Belgium e-mail: email@example.com
3 LUTH, Observatoire de Paris-Meudon, 5 place J. Janssen, 92195 Meudon, France e-mail: firstname.lastname@example.org
Accepted: 17 February 2007
Context.Direct detection of Earth-like planets around a nearby star is extremely difficult for ground-based telescopes equipped with the eXtreme Adaptative Optics system.
Aims.We propose to combine high-precision radial velocity with an ELT to detect extrasolar planets with a feasible coronagraph.
Methods.In this context, we investigated the detectability of Earth-like extrasolar planets with an ELT of 42 m equipped with the spectro-coronagraphic instrument in an eXtrem Adaptive Optics system. Those stellar residuals left uncorrected by the XAO wavefront correction (Strehl ratio >85%) system need to be calibrated. We propose calibrating them by the radial velocity measurement of the planet in a multiple spectrum correlation process.
Results.This method allows detection of Terrestrial planets with an ELT but requires a long exposure time (200 h)
Conclusions.The technique overcomes the main coronagraphic limitation due to the pinned and the low variable speckles and opens a way to detect directly exoplanets with large ground-based telescopes equipped with an efficient XAO system.
Key words: stars: planetary systems / techniques: spectroscopic / techniques: radial velocities / astrobiology
© ESO, 2007