High-resolution Ultraviolet-to-nearinfrared Characterization of Exoplanet Atmospheres

TL;DR

The paper discusses how the Habitable Worlds Observatory can revolutionize exoplanet atmospheric studies by enabling high-resolution spectroscopy across ultraviolet to near-infrared wavelengths, crucial for understanding atmospheric composition and mass loss.

Contribution

It proposes a comprehensive approach using HWO's broad spectral coverage and high resolution to analyze exoplanet atmospheres and their escape processes, advancing current observational capabilities.

Findings

HWO can achieve high-resolution spectroscopy (R > 60,000) from 100-1600 nm.

Simultaneous characterization of atmospheric composition, clouds, and thermal structure is feasible.

The approach can disentangle planetary signals from stellar activity.

Abstract

The Habitable Worlds Observatory (HWO) offers a unique opportunity to revolutionize our understanding of planetary formation and evolution. The goal of this Science Case Development Document (SCDD) is to investigate the physical and chemical processes that shape the composition and atmospheric mass loss in exoplanets. We review the key observables currently known as diagnostics of mass loss via transit observations, i.e., absorption lines of escaping hydrogen (Lyman-alpha), helium, and metals (Fe, Mg, C, O). We also explore the challenges to infer planetary formation processes based on atmospheric composition characterization. HWO could enable a broad, continuous coverage from far-ultraviolet to near-infrared spectroscopy (~100--1600 nm) at high resolution (R > 60, 000), which is essential to make these measurements, disentangle their planetary origin from stellar activity, and ultimately, contextualize the escape rates by simultaneously characterizing the composition, cloud predominance, and thermal structure of exoplanet atmospheres.