S22A0112

We propose IRCS spectro-astrometry of young stellar objects using AO, covering [NI]10400/10410 Å (doublet line), which is identified as a new promising tracer for photoevaporation. Photoevaporation is thought to be one of the most dominant disk dispersal processes, but its mechanism is little understood. Even the very basics of the process i.e., the major energy band is responsible for the process (e.g., FUV, EUV, or X-ray) is still unclear, and only ∼20 samples are observationally available, which hampers the overall understanding. Taking advantage of Subaru/IRCS with AO188, which allows for the highest spatial resolution among the NIR spectrometers on the existing 8–10 m class telescopes, this research aims at the followings. i) Directly locate the emitting region of [NI] lines and verify if the lines are in fact from outside of the critical radius of photoevaporation, R_g ≃ GM_* / c_s² ≃ 10 (M_* / M_⊙) AU, ii) Derive the physical parameters of the emitting gas (T and N_e) with high accuracy from the ratio of emission line flux of [NI] lines by spectroscopic diagnostics. We have selected targets that meet the best conditions (M_* ∼ 10 M_⊙ and D ≃ 350 pc) and have already confirmed [NI] lines detectable with the proposed observation.

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