Energetic Neutral Atoms from the Heliotail Direction and their Potential Source Regions Available to Purchase

The particle instrument CELIAS/HSTOF onboard SOHO is observing the energetic neutral atom (ENA) flux in the ecliptic plane since 1996. During quiet time periods, the ENA flux is well separated from the energetic ion flux, originating in the solar corona and/ or heliosphere. The instrument is capable to measure the energetic neutral hydrogen (ENH) and helium (ENHe) fluxes along the line‐of‐sight of the instrument field‐of‐view. We will discuss the neutral energetic flux measurements of hydrogen and helium in the 28 to 88 keV/n energy/mass range of CELIAS/HSTOF, focusing on the frequently increased fluxes from the tail direction of the heliosphere. Potential source regions might be co‐rotating interaction regions (CIRs) and the helium cone in the inner heliosphere, solar energetic particle events, accelerated pick‐up ions in the outer heliosphere and energetic neutral particles originating from the heliosheath region and beyond.