S20B0105abst
S20B0105
We propose high-resolution spectroscopy observation of a bright late-T dwarf Gl 229B (H = 14.36), which is the first brown dwarf discovered, by IRD aiming to robustly detect or exclude the absorption features of NH3, HCN, H2S, SH, and CO in H band by cross-correlation technique. As for HCN, H2S, and SH, if detected, it would be the first ever detection for brown dwarfs after the theoretical prediction of their existence for more than a decade. Indeed, from our simulation of spectrum and cross correlation signal of NH3 and HCN for Gl 229B, we expect seven and four sigma detection of their features, respectively, only for a single half night. While CO and NH3 features at other wavelengths have been already detected, detection/non-detection of their weaker H band features would enable us to further constrain their abundances. This observation is essential to constrain the strength of atmospheric mixing and temperature in deep atmosphere inaccessible by observations, which give us a valuable clue to the formation and evolution of brown dwarfs.
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