Science Seminars

9/8/2011 – IBEX

Speaker: Dave McComas
Date: Thursday, Sep 08, 2011
Time: 4pm
Location: Duane

Seminar Abstract:

The Interstellar Boundary Explorer (IBEX) mission has been remotely observing the global interaction of our heliosphere with the local interstellar medium for over two and a half years. Initially, IBEX generated the first all-sky maps of Energetic Neutral Atoms (ENAs) emanating in from the boundaries of our heliosphere over the energy range from ~0.1-6 keV. Using these observations, the IBEX team discovered a smoothly varying, globally distributed ENA flux overlaid by a narrow “ribbon” of significantly enhanced ENA emissions. Since the initial publications of these results in a special issue of Science magazine (November 2009), IBEX has completed four more energy-resolved sets of sky maps and discovered small but important time variations in the interaction, separated the ribbon from globally distributed ENA fluxes, measured the energy spectral shape and inferred ion source temperatures, and carried out many other observational and theoretical studies of the outer heliosphere. In addition, IBEX made 1) the first observations of ENAs produced by backscatter and neutralization of the solar wind from the lunar regolith, provided the first energy and angle resolved ENA images of the 1) subsolar magnetosheath, 2) magnetospheric cusps, and 3) terrestrial plasma sheet. New, direct IBEX observations of Interstellar Neutral (ISN) He atoms show that the speed and direction (the motion of the heliosphere with respect to the interstellar medium) is different than that thought from prior Ulysses observations. These observations also show evidence for a previously unknown and unanticipated secondary population of Helium. In addition, IBEX is providing the first direct quantitative measurements of the ISN H parameters and the first direct measurements of interstellar Ne and the interstellar Neon/Oxygen abundance ratio; this ratio is significantly different than the solar abundance ratio. Finally, IBEX was recently maneuvered into a unique, long-term stable orbit, which has a very low radiation environment and requires no orbit maintenance. Thus, IBEX will likely continue to provide revolutionary observations of numerous heliospheric, magnetospheric, and planetary phenomena for many years to come!