High-Resolution Dayside Spectroscopy of WASP-189b: Detection of Iron during the GHOST/Gemini South System Verification Run

TL;DR

This study presents high-resolution spectroscopy of the ultra-hot Jupiter WASP-189b using GHOST, detecting neutral iron in its atmosphere and demonstrating GHOST's capability for exoplanet atmospheric characterization.

Contribution

First high-resolution atmospheric detection of an exoplanet using GHOST, showcasing its potential for studying ultra-hot Jupiter atmospheres.

Findings

Detection of neutral iron at 7.5σ significance

Verification of a thermal inversion in WASP-189b's atmosphere

First atmospheric characterization of an exoplanet with GHOST

Abstract

With high equilibrium temperatures and tidally locked rotation, ultra-hot Jupiters (UHJs) are unique laboratories within which to probe extreme atmospheric physics and chemistry. In this paper, we present high-resolution dayside spectroscopy of the UHJ WASP-189b obtained with the new Gemini High-resolution Optical SpecTrograph (GHOST) at the Gemini South Observatory. The observations, which cover three hours of post-eclipse orbital phases, were obtained during the instrument's System Verification run. We detect the planet's atmosphere via the Doppler cross-correlation technique, and recover a detection of neutral iron in the planet's dayside atmosphere at a significance of 7.5$\sigma$ in the red-arm of the data, verifying the presence of a thermal inversion. We also investigate the presence of other species in the atmosphere and discuss the implications of model injection/recovery tests. These results represent the first atmospheric characterization of an exoplanet with GHOST's high-resolution mode, and demonstrate the potential of this new instrument in detecting and studying ultra-hot exoplanet atmospheres.