Assessing PLATO's Discovery Potential across Different Observing Strategies

Abstract

The PLATO mission, planned to launch in spring 2027, will observe a fixed Southern field, LOPS2, for at least 2 years with the goal of discovering and deriving precise parameters for planets as small as Earth around FGK dwarfs and sub-giants. Afterwards, PLATO could continue to monitor the same field or move to a Northern field, LOPN1, overlapping with the Kepler field. We assess these two observing strategies in terms of sensitivity of detecting small and long period planets, and subsequently we estimate yields for both observing strategies. Within this we account for including the Kepler data in the LOPN1 field, monitoring of up to 8 years of the LOPS2 field, and the sensitivity improvement from combining TESS and PLATO data since both fields have been and will be continued to be observed with TESS. We find that by monitoring both fields, and hence more stars, the total number of newly discovered planets is maximised. However, to optimise the number of discovered small and long periods planets, long-term monitoring of one field produces the best results. The combination of Kepler and PLATO data improves detection sensitivities; however, as this only covers a fraction of the LOPN1 field and stellar sample, it improves the yields of small and long period planets only marginally. Hence, to detect and characterise small and long period planets in this sparsely explored exoplanet parameter space, a longer continuous observation of the LOPS2 field is best.