Hydrogen line emission from accreting gas-giant planets
speaker: Yuhiko Aoyama
Abstract:
Gas giant planets such as Jupiter are mainly composed of hydrogen gas. They form in the circum-stellar gaseous disk (so-called protoplanetary disk) by gathering its surrounding gas. Recent instruments have successfully detected forming giant planets embedded in the protoplanetary disk by direct imaging. Particularly, the detection of hydrogen lines including H-alpha (Balmer-alpha) is a key to understanding their formation. Hydrogen lines require hot gas of ~10^4 K. However, at the hydrogen line emitting planets, the photospheric temperature is estimated as a few thousand K by IR observation. Therefore, hydrogen lines are thought to come from the gas accretion towards the forming planets.
In this talk, I will show our numerical model of hydrogen line emission at the accretion shock on the planetary surface. We confirmed the shock emission can reproduce the observation and estimated their accretion properties such as mass accretion rate by the flux and spectral profile of the observed hydrogen lines. Then, I will introduce the competitive line emission model of “magnetospheric accretion column” and how we can distinguish the emission mechanism with some future observations.