Hydrodynamic escape of nitrogen from Pluto

Abstract

Hydrodynamic escape of nitrogen from Pluto is studied by solving time-dependent hydrodynamic escape equations that treat the spatial distribution of EUV energy deposition realistically. Simulations show that the N2 hydrodynamic escape rate is ∼1 × 1028 molecules s-1 when Pluto is at 40 AU (its average orbital location) and solar activity level is at minimum. The N2 hydrodynamic escape rate is ∼2 × 1028 molecules s-1 when Pluto is at its perihelion (30 AU) and solar activity level is at maximum. Through hydrodynamic escape, Pluto may have lost ∼0.5% of its total mass over the age of the solar system. Comet-like interactions may occur between Pluto's atmosphere and the solar wind flow, which may be observed by the New Horizon mission. Copyright 2005 by the American Geophysical Union.