Effect of the Planet Shine on the Corona: Application to the Venusian Hot Oxygen

Abstract This paper presents a new derivation of the hot oxygen density in the Venusian upper exosphere (above 500 km) from Pioneer Venus Orbiter (PVO) ultraviolet spectrometer data, considering the effect of the solar photons backscattered by the oxygen atoms below ∼300 km (Venus shine), not included in past analysis, with a resonant scattering radiative transfer model. The Venus shine increases the volume emissivity of the hot oxygen corona by ∼60% compared to the direct solar illumination, and the O I 130.4 nm brightness measured by PVO is reproduced with a hot oxygen density reduced by 1.6 compared to the density deduced from past analysis. Therefore, this new hot oxygen density provides better constraints on the production rates of hot oxygen in the Venusian ionosphere or on the thermalization by collisions of the hot oxygen atoms.