The Study of Atmosphere of Hot Jupiters and Their Host Stars

What makes the study of exoplanetary atmospheres so hard is the extraction of its tiny signal from observations, usually dominated by telluric absorption, stellar spectrum and instrumental noise. The High Resolution Spectroscopy has emerged as one of the leading techniques for detecting atomic and molecular species (Birkby 2018), but although it is particularly robust against contaminant absorption in the Earth's atmosphere, the non-stationary stellar spectrum -- in the form of either Doppler shift or distortion of the line profile during planetary transits -- creates a non-negligible source of noise that can alter or even prevent the detection. Recently, significant improvements have been achieved by using 3D, radiative hydrodynamical (RHD) simulations for the star and Global Circulation Models (GCM) for the planet (e.g., Chiavassa & Brogi 2019, Flowers et al. 2019). However, these numerical simulations have been computed independently so far, while acquired spectra are the result of the natural coupling at each phase along the planet orbit. With our work, we aim at generating emission spectra of G,F, and K-type stars and Hot Jupiters and coupling them at any phase of the orbit. This approach is expected to be particularly advantageous for those molecules that are present in both the atmospheres (e.g., CO) and form in the same region of the spectrum, resulting in mixed and overlapped spectral lines. We also present the analysis of transmission spectra of the Hot Saturn WASP-20b, observed in the K-band of the recently upgraded spectrograph CRIRES+ at a resolution ~92, 000 during the first night of the Science Verification of the instrument and that led to a tentative detection of H2O.
Comment: 4 pages - Proceedings about the oral presentation given by the first author at the annual meeting of the French Society of Astronomy and Astrophysics (SF2A, http://www.sf2a.eu)