Heliospheric Energetic Neutral Hydrogen Atoms as observed with SOHO/CELIAS

M. Hilchenbach, K.C. Hsieh, D. Hovestadt, B. Klecker, H. Grünwaldt, F.M. Ipavich, P. Bochsler, and the CELIAS Team

Paper presented at the COSPAR meeting, July 12-19, 1998, Nagoya, Japan.

The time-of-flight mass spectrometer HSTOF of the CELIAS experiment on SOHO near the Lagrangian point L1 has the capability of detecting energetic neutral hydrogen atoms (ENHAs) between 55 and 80keV. We shall report on the observed ENHA flux of heliospheric origin. The flux is anisotropic and peaked in the anti-apex direction of the heliosphere. The implications of this observations on the existing models of energetic neutral atom (ENA) production in the heliosphere are discussed, i.e. the ENHA flux anisotropy and energy distribution resulting from the anomalous cosmic ray (ACR) protons transcharging on the LISM neutral atoms.

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Last Update: January 12, 1998, Peter Wurz