An empirically-based model of the upstream heliopause and outer heliosheath - Current status

We describe a simplified model of the outer heliosheath upstream of the heliopause in an attempt to extract the heliosheath properties from the IBEX-Lo neutral He observations. The distribution of incident He on the sky shows a primary beam surrounded by an irregular cloud of secondary particles. These secondaries are generated by charge-exchange interactions between the neutral primary beam, carrying the properties of the distant interstellar medium, and the nearby interstellar plasma that is deflected around the obstacle posed by the heliosphere. We construct an analytical model for the plasma flow around an arbitrarily-shaped obstacle and compute the resulting distribution of neutral He at IBEX, to compare with the observed He fluxes. Here, we report on the current status of this modelling effort. (paper)