S19A0106abst
S19A0106
So far, more than 40 of exoplanets were discovered by near-infrared direct imaging. Among them, HR8799 system is one of the most interesting objects because of several reasons: the system has at least 4 planets b,c,d,e, orbiting 15-70 AU from the parent star, with a mass of 5-7 Msun. Several molecules, CO, H2O, and CH4 were detected in their atmospheres. Their formation mechanism is still a debate. Are they formed from a circumstellar disk (i.e. core accretion), or formed via like a star formation process? To address this question, we propose to measure rotational velocity of the planets by the high-resolution spectroscopy with Infrared Doppler (IRD) instrument. Planet rotational velocity measurements will enable us to study a formation mechanism of planets, completely independent to the photometric and low-resolution spectroscopy conducted so far. Fortunately, the inclined orbit of HR8799 planets makes it suitable for measuring rotational velocities. To achieve our goal, both high spectral resolution (R>50,000) and high angular resolution (0.1 arcsec) is critical for robust detection of absorption lines of molecules. Thanks to the adaptive optics, the planet images can be spatially resolved from the parent star, which will lead to Β 100 times reduction of scattered star light at the position of the planets.
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