Ultra-hot Jupiter atmospheres at high spectral resolution

TL;DR

This paper discusses how high-resolution spectroscopy enables detailed study of ultra-hot Jupiter atmospheres, revealing unique chemical and physical properties due to extreme temperatures and spectral features.

Contribution

It highlights the potential of high-resolution spectroscopy to uncover atmospheric details of ultra-hot Jupiters that are inaccessible with lower resolution methods.

Findings

High temperatures allow refractory metals to exist in gas phase.

High-resolution spectroscopy can distinguish planetary signals from telluric and stellar lines.

Ultra-hot Jupiters exhibit distinct chemical and cloud properties compared to colder exoplanets.

Abstract

Observations of ultra-hot Jupiters offer an unprecedented opportunity to study the physics of some of the most extreme planetary atmospheres known. With exceedingly high amounts of irradiation blasting their upper atmospheres, ultra-hot Jupiters have dayside temperatures comparable to some late type stars enabling refractory metals otherwise condensed in colder planets to exist in the gas phase, all the while still maintaining comparatively cool nightsides. The ensuing intense temperature contrasts can give rise not only to strong day-to-night winds, but also to vastly different chemical and cloud properties on opposing hemispheres. With its ability to resolve spectral features that are unique to individual chemical species, high resolution spectroscopy can unambiguously disentangle atmospheric signals of exoplanetary origin, which follow a well-defined Keplerian motion, from stationary or pseudo-stationary telluric and stellar lines. Combined, the high temperature of ultra-hot Jupiters providing access to refractory metals with narrow spectral features and the ability of high-resolution spectroscopy to resolve said narrow lines provides access to a wealth of information about these atmospheres that would otherwise be unavailable at lower resolving powers or for other types of planets. In this chapter we explore some of the key physical and chemical transitions that differentiate ultra-hot Jupiters from their colder counterparts and highlight the unique opportunities arising from probing their atmospheres using high resolution spectroscopy.