Astronomy Colloquium

As we all know, JWST is revolutionizing exoplanet atmospheric characterization. But the next revolution is already brewing, in the cauldrons of large ground-based telescopes and distilled through high-resolution spectrographs. Using a technique called high-resolution cross-correlation spectroscopy (HRCCS), we can extract an exoplanet's signal from the otherwise overwhelming stellar and telluric components. By cross-correlating with a template planet spectrum, we can identify a signal whose Doppler shift during the observation matches the orbital motion of the planet. While we do not directly measure a planet's spectrum with this technique, the data do contain information about the detailed shapes of the planetary spectral lines. For hot Jupiters—those high signal-to-noise targets with extreme atmospheric physics—HRCCS provides unique constraints on their rotation rates and wind speeds, as well as more subtle signatures of their three-dimensional atmospheric structures. In this talk, I will begin with an overview of the complex physics that shapes hot Jupiter atmospheres and why this remains such a challenging topic. I will then describe the work that my group has done to link the 3-D temperature and wind structures of hot Jupiters to signatures observable with HRCCS. I will showcase some pioneering observational results from HRCCS, while also highlighting some important subtleties that demand a nuanced approach to data interpretation. Finally, I will end with a vision for the ELT revolution, whose incredible advances we are not yet prepared to face.