Estimating the number of planets that PLATO can detect

TL;DR

This study estimates the number of exoplanets the upcoming PLATO mission can detect, considering various factors like planetary size, period, and observation strategy, to inform future exoplanet research and mission planning.

Contribution

We developed the PYPE estimator to predict PLATO's exoplanet yield using occurrence rates and detection efficiencies, providing detailed insights into expected detection numbers under different scenarios.

Findings

Expected thousands to tens of thousands of planets detected.

Minimum of 500 Earth-sized planets expected.

Detection rates vary with observation strategy and duration.

Abstract

The PLATO mission is scheduled for launch in 2026. This study aims to estimate the number of exoplanets that PLATO can detect as a function of planetary size and period, stellar brightness, and observing strategy options. Deviations from these estimates will be informative of the true occurrence rates of planets, which helps constraining planet formation models. For this purpose, we developed the Planet Yield for PLATO estimator (PYPE), which adopts a statistical approach. We apply given occurrence rates from planet formation models and from different search and vetting pipelines for the Kepler data. We estimate the stellar sample to be observed by PLATO using a fraction of the all-sky PLATO stellar input catalog (PIC). PLATO detection efficiencies are calculated under different assumptions that are presented in detail in the text. The results presented here primarily consider the current baseline observing duration of four years. We find that the expected PLATO planet yield increases rapidly over the first year and begins to saturate after two years. A nominal (2+2) four-year mission could yield about several thousand to several tens of thousands of planets, depending on the assumed planet occurrence rates. We estimate a minimum of 500 Earth-size (0.8-1.25 RE) planets, about a dozen of which would reside in a 250-500d period bin around G stars. We find that one-third of the detected planets are around stars bright enough (V $\leq 11$) for RV-follow-up observations. We find that a three-year-long observation followed by 6 two-month short observations (3+1 years) yield roughly twice as many planets as two long observations of two years (2+2 years). The former strategy is dominated by short-period planets, while the latter is more beneficial for detecting earths in the habitable zone.