The ARIEL Mission Reference Sample

The main purpose of this paper is to identify an optimal list of targets observable by ARIEL (Atmospheric Remote-sensing Exoplanet Largesurvey), one of the three European Space Agency M4 mission candidates competing for a launch in 2026. Here we describe the assumptions made to estimate an optimal sample of exoplanets - including both the already known exoplanets and the "expected" ones yet to be discovered - observable by ARIEL and define a realistic mission scenario. The current ARIEL design enables the observation of ~1000 planets during its four year mission lifetime. This nominal list of planets is expected to evolve over the years depending on the new exoplanet discoveries.