Characterizing exoplanetary atmospheres with SPIRou

Ground-based high-resolution spectroscopy allows us to probe the chemical composition and atmospheric dynamics of hot jupiters through the Cross-Correlation Function method. This requires however careful data processing and development of analysis tools in order to extract such a faint exoplanetary signal from the overwhelming telluric and stellar contributions. With a high spectral resolution power of 70,000 and a large continuous spectral range between 0.9 and 2.5 microns, the near-infrared spectro-polarimeter SPIRou on the CFHT is a powerful instrument for exoplanet atmosphere characterization since its first light in 2018. I will present our analysis of SPIRou primary transit observations of some short-period exoplanets. Preliminary results regarding the detection of the metastable He triplet and molecules in the hot jupiters HD 189733b and HD 20458b, the warm neptunes GJ 3470b and Au Mic b, the mini neptune GJ 1214b, the hot neptune WASP-127b, and the warm saturn WASP-69b, will be presented.

Figure 1: Cross correlation between observed and synthetic spectra of HD189733b (expressed in S/N ratio) calculated over a grid of velocity parameters Kp (radial velocity semi-amplitude) and V₀ (additional Doppler shift of atmospheric lines at mid-transit). The correlation is maximum at the expected position in this parameter space [1]. The model spectra include water vapor as the only molecular absorber.

References :

[1] Boucher, A., Darveau-Bernier, A., Pelletier, S., Lafrenière, D., Artigau, E., et al., (2021). Characterizing Exoplanetary Atmospheres at High Resolution with SPIRou: Detection of Water on HD 189733 b. The Astronomical Journal, American Astronomical Society, 162 (6), pp.233.