Structures and Spectra at the Interface of the Heliosphere and Interstellar Medium: Energetic Neutral Atom (ENA) Sky Maps from the Interstellar Boundary Explorer

The Interstellar Boundary Explorer (IBEX) has obtained all-sky images of energetic neutral atoms (ENAs) emitted from the heliosheath, located between the termination shock of the solar wind and the local interstellar medium (LISM). The spectral variations over the energy range 0.3-6 keV in the ENA all-sky maps reveal an unexpected new picture of the outer boundary of the heliosphere, including the discovery of a circular ribbon of enhanced ENA emission, spectral features suggesting global ordering by heliospheric latitude, and a dominant role played by the non-thermal proton populations. The IBEX spectral measurements enable unprecedented insight into the underlying structure and dynamics of the heliosheath.