Exoplanet atmospheres in the view of low- and high-resolution transmission spectroscopy

Exoplanet atmospheres in the view of low- and high-resolution transmission spectroscopy 




摘要: Exoplanet atmospheres may carry chemical imprints (e.g. metallicity, C/O ratio) to link to planet formation and evolution history. In the past ten years, transmission spectroscopy has become the most efficient technique to unveil composition, chemistry, structure, and dynamics for exoplanet atmospheres. HST/WFC3 has revealed that a large collection of exoplanets exhibits the water absorption signature at 1.4 micron. However, the determination of water abundances is somewhat hindered by the potential presence of clouds and hazes owing to the degeneracy between pressure and abundance. Fortunately, low-resolution optical spectroscopy can help disentangle this degeneracy and also mitigate contamination from stellar surface heterogeneity. On the other hand, spectroscopy at high-resolution is capable of resolving the fine structure of absorption lines from atoms and ions in the upper atmosphere, offering the opportunity to study atmospheric heating and dynamics. In this talk, I will present the latest results from our transit spectroscopy survey using the low-resolution optical spectrograph at the 10.4 m GTC telescope. This survey has revealed a variety of cloudy, hazy, and clear alien worlds. In particular, I will highlight the role of alkali metals in characterizing exoplanet atmospheres. Furthermore, I will present our recent efforts to resolve the absorption line cores of hydrogen, helium, and alkali metals using high-precision Doppler spectrographs (e.g. HARPS-N, CARMENES, ESPRESSO), which hopefully can reveal the underlying physical and chemical processes.


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