# An Updated Study of Potential Targets for Ariel

## TL;DR

This study evaluates Ariel's potential to observe and characterize a diverse range of exoplanets, including smaller Earth-sized planets, using simulations to optimize target selection for the mission's primary objectives.

## Contribution

It introduces a comprehensive simulation-based assessment of Ariel's observational capabilities and proposes a dynamic target list optimization strategy for the mission.

## Key findings

- Approximately 2000 known and predicted exoplanets could be characterized by Ariel.
- A diverse Mission Reference Sample of 1000 planets is feasible within the mission duration.
- Ariel can perform in-depth observations of smaller, Earth-sized, and Super-Earth planets despite challenges.

## Abstract

Ariel has been selected as ESA's M4 mission for launch in 2028 and is designed for the characterisation of a large and diverse population of exoplanetary atmospheres to provide insights into planetary formation and evolution within our Galaxy. Here we present a study of Ariel's capability to observe currently-known exoplanets and predicted TESS discoveries. We use the Ariel Radiometric model (ArielRad) to simulate the instrument performance and find that ~2000 of these planets have atmospheric signals which could be characterised by Ariel. This list of potential planets contains a diverse range of planetary and stellar parameters. From these we select an example Mission Reference Sample (MRS), comprised of 1000 diverse planets to be completed within the primary mission life, which is consistent with previous studies. We also explore the mission capability to perform an in-depth survey into the atmospheres of smaller planets, which may be enriched or secondary. Earth-sized planets and Super-Earths with atmospheres heavier than H/He will be more challenging to observe spectroscopically. However, by studying the time required to observe ~110 Earth-sized/Super-Earths, we find that Ariel could have substantial capability for providing in-depth observations of smaller planets. Trade-offs between the number and type of planets observed will form a key part of the selection process and this list of planets will continually evolve with new exoplanet discoveries replacing predicted detections. The Ariel target list will be constantly updated and the MRS re-selected to ensure maximum diversity in the population of planets studied during the primary mission life.