The First Confirmed Detection of a Metal Hydride in an Exoplanet

Because hot Jupiters span a similar temperature range to that of warmer brown dwarfs, comparisons between the two classes provide insights into the physics of the atmospheres for both hot Jupiters and brown dwarfs. In L dwarfs, molecules like FeH and CrH are ubiquitous and are used to determine their temperature or spectral type. However, these molecules have no previously confirmed detections in exoplanets, despite numerous, well-studied exoplanets having comparable temperatures to that of L dwarfs (~1300 – 2400 K). In this talk, we present the first confirmed detection of any metal hydride in an exoplanet with our detection of CrH in WASP-31b using high-resolution transmission spectroscopy from GRACES and UVES. We discuss the statistical methods involved in confirming the detection. We also consider the implications of detections of metal hydrides for future hot Jupiter atmosphere research.