FLASH Talks: Jake Turner (Cornell University) & Aritra Chakrabarty (Universidad Adolfo Ibáñez)

Friday, 03 February 2023 noon — 1 p.m. MST

NOIRLab Headquarters | 950 North Cherry Ave., Tucson, AZ 85719

Jake Turner (Cornell University) & Aritra Chakrabarty (Universidad Adolfo Ibáñez))

Jake Turner, Cornell University
Exploring the diversity of exoplanet atmospheres at high spectral resolution with Gemini-N/GRACES

Following over two decades of discoveries, we now have a substantial sample of exoplanets that can be characterized in detail with current facilities, enabling the emerging field of comparative exoplanetology. Studies of hot Jupiters at low spectral resolution have revealed a rich diversity of planetary atmospheres that range from cloudy to cloud-free, and exhibit scattering slopes from aerosols and absorption features from species such as Na, K, and TiO. High-spectral-resolution observations are emerging as a particularly powerful and robust probe of exoplanetary atmospheres. The use of high-resolution spectroscopy, where we can uniquely identify atoms and molecules, distinguishes it from other comparative studies. These type of observations can place strong constraints on the abundances, altitudes, and local temperatures where each species forms. High-resolution observations have also been used to measure atmospheric winds, structure, and planetary rotation. Our Gemini Large and Long Program "Exploring the Diversity of Exoplanet Atmospheres at High Spectral Resolution" (Exoplanets with Gemini Spectroscopy, or ExoGemS for short) seeks to advance the field by carrying out one of the first comparative studies of exoplanet atmospheres at high spectral resolution in the optical with Gemini-N/GRACES. In total, we hope to observe 40 exoplanets for our high-spectral-resolution survey. Currently, we have observed over a dozen exoplanets with GRACES across a large parameter space. In this talk, we discuss the results of the survey thus far. Some highlights include detecting neutral sodium, ionized calcium, and asymmetric iron in the atmosphere of ultra-hot Juptier WASP-76b and a tentative detection of chromium hydride on the low-density hot Jupiter WASP-31b. Our WASP-76b results indicate that the atmospheric layers probed from our observations are much hotter than expected from hydrodynamic and radiative equilibrium. In summary, our survey hopes to advance our understanding of the diversity of exoplanet atmospheres in significant ways, and shed new light on how this diversity depends on the physical properties of the planets and their host stars.

Aritra Chakrabarty, Universidad Adolfo Ibáñez
Synergic Characterization of Exoplanets in the era of JWST
The era of JWST and future big-budget missions will give us a unique opportunity to study and characterize the detected exoplanets in greater detail to understand their formation and evolution mechanisms. A more accurate interpretation of these studies calls for precise modeling of the atmospheric processes of the planets. I will present the upgraded models we have developed for the transmission spectra and reflection phase curves of exoplanets by incorporating diffuse scattering of light in the atmospheres. The effect of scattering on the transmission spectra is especially important to model the effects of aerosols present in their atmospheres since atmospheric clouds are one of the major sources of degeneracy and hence limit such studies. The models match well with the previous HST observations of the hot Jupiters. The degeneracy due to clouds can be further reduced and the properties of the condensates can be studied in greater detail by complementing the existing photometric and spectroscopic techniques with the emerging polarimetric techniques. I will present our state-of-the-art polarization models of exoplanets we have developed which will play a pivotal role in guiding the ground-based facilities and space-bound missions planned for polarimetric studies of exoplanets.