Forecasting the detectability of known radial velocity planets with the upcoming CHEOPS mission

TL;DR

This paper predicts the detectability of known radial velocity exoplanets with the upcoming CHEOPS mission by estimating their transit signals and magnitudes, aiding mission planning and follow-up observations.

Contribution

It introduces a probabilistic framework to estimate transit parameters for RV planets, enabling better detection predictions for CHEOPS.

Findings

Most RV planets are likely detectable by CHEOPS.

22 mini-Neptunes and 82 Neptune-sized planets are suitable for detection.

Over 80% of these planets have V < 10, ideal for follow-up.

Abstract

The Characterizing Exoplanets Satellite (CHEOPS) mission is planned for launch next year with a major objective being to search for transits of known RV planets, particularly those orbiting bright stars. Since the radial velocity method is only sensitive to planetary mass, the radii, transit depths and transit signal-to-noise values of each RV planet are, a-priori, unknown. Using an empirically calibrated probabilistic mass-radius relation, forecaster (Chen & Kipping 2017a), we address this by predicting a catalog of homogeneous credible intervals for these three keys terms for 468 planets discovered via radial velocities. Of these, we find that the vast majority should be detectable with CHEOPS, including terrestrial bodies, if they have the correct geometric alignment. In particular, we predict that 22 mini-Neptunes and 82 Neptune-sized planets would be suitable for detection and that more than 80% of these will have apparent magnitude of V < 10, making them highly suitable for follow-up characterization work. Our work aims to assist the CHEOPS team in scheduling efforts and highlights the great value of quantifiable, statistically robust estimates for upcoming exoplanetary missions.