Local time variations of the hydrogen corona observed by SPICAV-UV/VEX

Jean-Yves Chaufray (1) , Jean-Loup Bertaux (2) , Eric Quémerais (1) , François Leblanc (1)

1 HELIOS - LATMOS
2 PLANETO - LATMOS

As all the terrestrial planets, Venus is surrounded by an hydrogen corona coming from the photodisso-ciation of the water vapor followed by its vertical transport at very high altitudes. From the UV observations of the resonant scattering Lyman-alpha emission , two components have been observed in this corona. A cold component corresponding to hydrogen population at equilibrium with the global atmosphere dominant below ~ 2000 km. A suprathermal component, produced by collisions between energetic protons with the cold component in the upper atmosphere. Due to its large energy, this hot population is able to reach very high altitudes, and escape and becomes dominant above ~4000 km (e.g. Ber-taux et al. 1982)

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]; Astrophysique stellaire et solaire [astro-ph.SR]

Jean-Yves Chaufray, Jean-Loup Bertaux, Eric Quémerais, François Leblanc. Local time variations of the hydrogen corona observed by SPICAV-UV/VEX. International Venus Conference 2016, Apr 2016, Oxford, United Kingdom. ⟨insu-01298370⟩