Speaker
Description
We aim to characterize transiting exoplanets spanning a wide range of sizes, masses and effective temperatures using a variety of high-resolution spectrographs, including through our on-going Gemini Large Program “Exploring the Diversity of Exoplanet Atmospheres at High Spectral Resolution” (ExoGemS, for short) with Gemini-N/GRACES. Here I will share a few early results from ExoGems, and present our new, complementary study of GJ 486b, a 1.3-Earth-radius planet around a nearby M dwarf. Given its high transmission spectroscopy metrics, GJ 486b is a compelling target for constraining an atmosphere in the terrestrial size regime. We observed three planetary transits with Subaru/IRD, Gemini-S/IGRINS and CFHT/SPIRou, and searched for absorption by a multitude potential atmospheric species. We are able to rule out a H/He-dominated atmosphere with solar abundances to a confidence of >5σ and a 100% water atmosphere to a confidence of 3σ. We also investigate the implications of our results for the upcoming JWST transit observations of GJ 486b. Our findings suggest that terrestrial planets orbiting M-dwarf stars may experience significant atmospheric loss.
