(Proposal ID) S17B-130 (PI) Kotani, Takayuki (Proposal Title) Searching for signatures from accreting extra-solar gas giant planets (Abstract) So far several exoplanets were discovered by NIR direct imaging, which are giant Jupiter-like planets orbiting at a distance over tens of AU around young stars. They are young, hot giant planets which could have been formed by the so-called "hot-start", but such a planet could be an exceptional case that cannot be explained by the core-accretion model. To verify the current planet- formation theory, a direct way is to observe a site of gas accretion onto a planet in a circumstellar disk. Even if there are no report of planet detection by NIR imaging in their cirucumstellar disk, a planet formation could be possible if a planet is formed by "cold-start" and too cold to be detected in the NIR. We propose a method to study accreting gas giant planet by the detection of H-alpha emission from a circumplanetary disk. Our study shows significant amount of gas accretion energy onto a protoplanet can be emitted by the H-alpha light which will largely relax the contrast between a star and a planet. To detect accreting planets, we will use SCExAO/VAMPIRES and CHARIS to separate a planet signal from scattered star light spatially and spectrally. We estimated a 5-20 Mjup planetary-mass object can be detected around nearby young stars.