Тип публикации: статья из журнала
Год издания: 2015
Идентификатор DOI: 10.1051/0004-6361/201424256
Ключевые слова: planets and satellites: formation, planets and satellites: terrestrial planets, planets and satellites: atmospheres, stars: solar-type, Sun: UV radiation, celestial mechanics, Astrophysics, Atmospheric temperature, Carbon dioxide, Energy transfer, Fluid dynamics, Hydrodynamics, Planets, Upper atmosphere, Stars: solar types, Sun:UV radiation, Terrestrial planets, Satellites
Аннотация: Aims. We investigate the influence of impacts of large planetesimals and small planetary embryos on the early Martian surface on the hydrodynamic escape of an early steam atmosphere that is exposed to the high soft X-ray and extreme-ultraviolet (EUV) flux of the young Sun. Methods. Impact statistics in terms of number, masses, veloПоказать полностьюcities, and angles of asteroid impacts onto early Mars are determined via n-body integrations. Based on these statistics, smoothed particle hydrodynamics (SPH) simulations result in estimates of energy transfer into the planetary surface material and the resulting surface heating. For the estimation of the atmospheric escape rates we applied a soft X-ray and EUV absorption model and a 1D upper atmosphere hydrodynamic model to a magma ocean-related catastrophically outgassed steam atmosphere with surface pressure values of 52 bar H2O and 11 bar CO2. Results. The estimated impact rates and energy deposition onto an early Martian surface can account for substantial heating. The energy influx and conversion rate into internal energy is probably sufficient to keep a shallow magma ocean liquid for an extended period of time. Higher surface temperatures keep the outgassed steam atmosphere longer in vapor form and therefore enhance its escape to space within similar to 0.6 Myr after its formation.
Журнал: ASTRONOMY & ASTROPHYSICS
Выпуск журнала: Vol. 574
ISSN журнала: 00046361
Место издания: LES ULIS CEDEX A
Издатель: EDP SCIENCES S A