Standing on the Shoulders of Giants: A Comprehensive Spectroscopic Survey of Transiting & High-Contrast Giant Planets

TL;DR

This paper proposes a comprehensive spectroscopic survey combining transit and high-contrast techniques to study giant planet compositions, formation, and evolution across various temperatures, distances, and ages, aiming to answer fundamental questions about their origins.

Contribution

It introduces an integrated observational approach to analyze a wide range of giant planets, bridging the gap between different formation pathways and advancing understanding of planetary origins.

Findings

Distinct formation pathways identified for transiting and directly imaged planets

Spectroscopic data reveal compositional differences across temperature and orbital ranges

Holistic view of giant planet formation and evolution proposed

Abstract

We propose a comprehensive survey of giant planets ranging from close-in highly irradiated hot Jupiters to young, wide-orbit directly imaged planets. The combination of two established techniques for probing planetary atmospheric compositions (time-series transit observations and high-contrast spectroscopy) will provide an unprecedented window into gaseous planet compositions across a range of equilibrium temperatures (100-2000 K), orbital separations (0.1-100 au), and system ages (10 Myr-1 Gyr). To-date, compositional measurements of both transiting and directly imaged planets suggest two distinct formation pathways: star-like formation for directly imaged planets and planet-like formation for transiting planets. By leveraging the combined technical and theoretical expertise of the transiting and direct imaging communities, we can obtain a holistic view of giant planet formation, migration, accretion, and evolution. From the results of this comprehensive program, we will begin to answer one of the fundamental outstanding questions in our understanding of giant planets: where and how in the protoplanetary disk do giant planets form?