The Interstellar Boundary Explorer (IBEX):

Abstract

The Interstellar Boundary Explorer (IBEX) mission is exploring the frontiers of the heliosphere where energetic neutral atoms (ENAs) are formed from charge exchange between interstellar neutral hydrogen atoms and solar wind ions and pickup ions. The geography of this frontier is dominated by an unexpected nearly complete arc of ENA emission, now known as the IBEX 'Ribbon'. While there is no consensus agreement on the Ribbon formation mechanism, it seems certain this feature is seen for sightlines that are perpendicular to the interstellar magnetic field as it drapes over the heliosphere. At the lowest energies, IBEX also measures the flow of interstellar H, He, and O atoms through the inner heliosphere. The asymmetric oxygen profile suggests that a secondary flow of oxygen is present, such as would be expected if some fraction of oxygen is lost through charge exchange in the heliosheath regions. The detailed spectra characterized by the ENAs provide time-tagged samples of the energy distributions of the underlying ion distributions, and provide a wealth of information about the outer heliosphere regions, and beyond.

The heliosphere—blowing in the interstellar wind

“…The geometrical structure of the Ribbon is reproduced by MHD heliosphere models that suggest the Ribbon originates 10-100 AU upstream of the heliopause [13,16,17,18,19]. In the models, the Ribbon is displaced towards the equator of the undistorted ISMF (which corresponds to sightlines perpendicular to the distant ISMF direction) as either the field strength becomes stronger [17,18], or as the ribbon formation region moves further from the heliopause [20].…”