Improving Earth-like planets' detection with an ELT: the differential radial velocity experiment
Résumé
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.
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