ExoGemS Detection of a Metal Hydride in an Exoplanet Atmosphere

TL;DR

This paper reports the first high-resolution detection of chromium hydride (CrH) in an exoplanet atmosphere, specifically in WASP-31b, advancing our understanding of atmospheric composition and classification.

Contribution

The study provides the first high spectral resolution detection of a metal hydride in an exoplanet atmosphere, confirming CrH presence in WASP-31b.

Findings

CrH detected at 5.6σ confidence in WASP-31b

First high-resolution detection of a metal hydride in an exoplanet atmosphere

Supports the role of metal hydrides in exoplanet atmospheric studies

Abstract

Exoplanet atmosphere studies are often enriched by synergies with brown dwarf analogs. However, many key molecules commonly seen in brown dwarfs have yet to be confirmed in exoplanet atmospheres. An important example is chromium hydride (CrH), which is often used to probe atmospheric temperatures and classify brown dwarfs into spectral types. Recently, tentative evidence for CrH was reported in the low-resolution transmission spectrum of the hot Jupiter WASP-31b. Here, we present high spectral resolution observations of WASP-31b's transmission spectrum from GRACES/Gemini North and UVES/VLT. We detect CrH at 5.6$\sigma$ confidence, representing the first metal hydride detection in an exoplanet atmosphere at high spectral resolution. Our findings constitute a critical step in understanding the role of metal hydrides in exoplanet atmospheres.