Scientific Colloquium
May 21, 2010

"Science Results from the Interstellar Boundary Explorer - IBEX"

Global images of the heliosphere’s interaction with the local interstellar medium have recently been published using first observations from the Interstellar Boundary Explorer (IBEX) mission [McComas et al., Science, 326, 5955, 2009 and related articles in the same issue]. IBEX observes energetic neutral atoms (ENAs) emanating in from the interaction region at the edge of the heliosphere. IBEX observations cover the energy range from <100 eV – 6 keV, which includes the important populations produced by both the solar wind and heliospheric pickup ions charge exchanging and producing ENAs in potentially both the inner and outer heliosheath (inside and out side the heliopause). In IBEX’s first sky maps, we discovered a narrow, bright ribbon of ENA emissions unpredicted by any prior models or theories. This ribbon is superposed on more gradually spatially varying globally distributed ENA flux, which is ordered by both the solar wind structure and the Sun’s direction of motion through the interstellar medium. The ribbon appears to be ordered by the local interstellar magnetic field, which indicates that the external galactic environment somehow strongly imprints the heliosphere. This talk summarizes the published IBEX observations and explanations that were put forward for generating the ribbon and shows new IBEX observations, which demonstrate that while the ribbon structure is largely stable, the detailed ENA emissions are in fact evolving over the six months between IBEX’s first and second sky maps.

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