PREPRINT
4C017C3D-DA06-4CF3-8016-D032440DBA19

# Detection Feasibility of H${}_{2}$ in Ultra-hot Jupiter Atmospheres

Anastasia Morgan, P. Wilson Cauley, Kevin France, Allison Youngblood, Tommi T. Koskinen
arXiv:2207.05963

Submitted on 13 July 2022

## Abstract

Ultra-hot Jupiters (UHJs) have recently been the focus of several atmospheric studies due to their extreme properties. While molecular hydrogen (H${}_{2}$) plays a key role in UHJ atmospheres, it has not been directly detected on an exoplanet. To determine the feasibility of H${}_{2}$ detection via transmission spectroscopy of the Lyman and Werner bands, we modeled UHJ atmospheres with H${}_{2}$ rotational temperatures varying from 2000 K to 4000 K orbiting A-type stars ranging from ${T}_{eff}$ = 8,500 K to ${T}_{eff}$ = 10,300 K. We present simulated transmission spectra for each planet-star temperature combination while adding Poisson noise varying in magnitude from 0.5% to 2.0%. Finally, we cross-correlated the spectra with expected atmospheric H${}_{2}$ absorption templates for each temperature combination. Our results suggest that H${}_{2}$ detection with current facilities, namely the Hubble Space Telescope, is not possible. However, direct atmospheric transmission spectroscopy of H${}_{2}$ may be viable with future UV-capable flagship missions.

## Preprint

Subject: Astrophysics - Earth and Planetary Astrophysics