Predictions for Astrometric and Orbit Retrieval of Confirmed Exoplanets with Roman Space Telescope Coronagraphy

With the recent application of coronagraph instruments to the field of exoplanet science, the range of detectable exoplanets has expanded drastically. The Roman Space Telescope will introduce an even deeper contrast regime, with the ability of its Coronagraph Instrument (CGI) to image cold Jovian exoplanets directly in reflected visible light. In this talk, we share predictions for the mass and orbit retrieval of such planets using CGI.

We have modeled the astrometry and flux of a preliminary “shortlist” of confirmed exoplanets that could be ideal targets for CGI observation based on their known characteristics. For planets whose exact mass and orbit inclination are unknown (as is the case with most planets discovered through radial velocity measurements), we model a range of inclination cases from 20- to 90-degrees and infer the remainder of the orbital parameters necessary for modeling. For each of these planets and inclination cases, we analyze the simulated data assuming only a few available observation epochs. By comparing the “true” planet parameters to the “measured” parameters that we extract, we predict the ability of the Roman CGI to perform orbit and mass retrieval of the target planets.

This work is a critical step in determining the best target planets to image in the Roman CGI primary mission, and it provides insight into the geometrical constraints of exoplanet characterization and orbit retrieval with direct imaging.