Scientific Colloquium
May 21, 2010
DAVID MCCOMAS
SOUTHWEST RESEARCH INSTITUTE
"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.