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AGU: Journal of Geophysical Research, Planets

 

Keywords

  • Venus
  • energetic neutral atoms

Index Terms

  • Planetary Sciences: Solar System Objects: Venus
Abstract
Cited By (0)
 

Abstract

Tailward flow of energetic neutral atoms observed at Venus

A. Galli

Physikalisches Institut, Universität Bern, Bern, Switzerland

M.-C. Fok

Geospace Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA

P. Wurz

Physikalisches Institut, Universität Bern, Bern, Switzerland

S. Barabash

Instituted för Rymdfysik, Kiruna, Sweden

A. Grigoriev

Instituted för Rymdfysik, Kiruna, Sweden

Y. Futaana

Instituted för Rymdfysik, Kiruna, Sweden

M. Holmström

Instituted för Rymdfysik, Kiruna, Sweden

A. Ekenbäck

Instituted för Rymdfysik, Kiruna, Sweden

E. Kallio

Finnish Meteorological Institute, Helsinki, Finland

H. Gunell

Department of Physics, West Virginia University, Morgantown, West Virginia, USA

The Analyzer of Space Plasma and Energetic Atoms (ASPERA-4) experiment on Venus Express provides the first measurements of energetic neutral atoms (ENAs) from Venus. The results improve our knowledge on the interaction of the solar wind with a nonmagnetized planet and they present an observational constraint to existing plasma models. We characterize the tailward flow of hydrogen ENAs observed on the nightside by providing global images of the ENA intensity. The images show a highly concentrated tailward flow of hydrogen ENAs tangential to the Venus limb around the Sun's direction. No oxygen ENAs above the instrument threshold are detected. The observed ENA intensities are reproduced with a simple ENA model within a factor of 2, indicating that the observed hydrogen ENAs originate from shocked solar wind protons that charge exchange with the neutral hydrogen exosphere.

Received 31 January 2008; accepted 26 August 2008; published 2 December 2008.

Citation: Galli, A., M.-C. Fok, P. Wurz, S. Barabash, A. Grigoriev, Y. Futaana, M. Holmström, A. Ekenbäck, E. Kallio, and H. Gunell (2008), Tailward flow of energetic neutral atoms observed at Venus, J. Geophys. Res., 113, E00B15, doi:10.1029/2008JE003096.

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