[PAE22-06] FUV-driven atmospheric escape from hot Jupiters
Keywords:Hot Jupiter, Atmospheric Escape
Recent theoretical studies of atmospheric escape from hot Jupiters incorporate the Extreme-UV (EUV; >13.6 eV) heating. EUV heats the gas through photoionization of hydrogen. It does not yield any metallicity-dependent trend. On the hand, some recent observations suggest that sub-Jupiter desert depends on the metallicity of the central star. There can be other heating processes which depends on metallicity.
In this study, we show that Far-UV (FUV; <13.6eV) drives atmospheric escape, using hydrodynamical simulation including radiative transfer and non-equilibrium chemistry. FUV can heat gas through the photoelectric effect of dust grains. The process is well known in the study of inter-stellar medium, but not considered in the atmospheric escape studies.
We find that FUV can drive atmospheric escape if the central star is hot (>6000K), and close-in giant planets around the hot stars can evaporate in ~100Myr. We also find that FUV-driven atmospheric escape depends on the metallicity of the planetary atmosphere and the central star. The heating rate and the mass loss rate increase in the case of metal-rich planets. However, both the rates decrease for the case of metal-rich central stars because FUV fluxes decrease in the metal-rich stars. We discuss the FUV-driven atmospheric escape and its dependence on the metallicity of planets and stars.