Science Seminars

Characterizing Extrasolar Atmospheres with High Resolution Cross-Correlation Spectroscopy

Speaker: Mike Line (ASU)
Date: Thursday, Jan 20, 2022
Time: 4:00 PM
Location: Zoom

Seminar Abstract:

The field of exoplanet characterization has matured to the point where we can begin to answer fundamental questions regarding planetary climate, composition, and formation, providing context for understanding our own solar system planets. The community has leveraged the power of numerous ground-and space-based observatories to find and characterize a diverse range of planets ranging from hot Jupiter’s to terrestrial-sized, potentially habitable worlds. Much of the successful atmospheric characterization work to date has focused on results from low-resolution spectroscopic/photometric (LRS, R<~1000) observations of transiting exoplanets from space-based instruments like Hubble and Spitzer. However the low resolution and sparse wavelength coverage of available instruments are unable to break key modeling degeneracies, preventing us from adequately constraining basic atmospheric properties. A powerful emerging ground-based approach for characterizing exoplanet atmospheres is high resolution (R~>30,000) cross-correlation spectroscopy (HRCCS). HRCCS leverages the planetary Doppler shift of the large number of molecular lines attainable at high resolutions combined with large ground-based apertures to robustly detect molecules. This is a powerful technique and will be at the forefront of exoplanet atmosphere characterization over the next decade+. I will provide an overview of the HRCCS method as well as some of the theoretical and computational challenges, including placing such an approach within a Bayesian modeling framework. I will also share a recent analysis of observations of a hot Jupiter obtained with the IGRINS instrument on Gemini South, resulting in carbon and oxygen abundance precisions comparable to those obtained for our solar system planets.