S21A0062

In the formation theory of gas-giants, C (carbon)-rich atmospheres are expected for in-situ formation while significant migration should result in O (oxygen)-rich atmospheres. Atmospheric molecules having carbon or oxygen can be tracers of a C-rich or O-rich atmosphere of gas-giants. We propose the first observation of self-luminous planets HR8799bcde to search for HCN, CO, C2H2, CH4, and H2O using the high-dispersion coronagraphy combined with cross-correlation. Because HDC using REACH can significantly suppress the leakage from host starlight, we can search for such species by high-dispersion spectroscopy for the first time. In addition, these observations will constrain the rotation rates of these planets, thanks to the high spectral resolution of REACH.

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