Interstellar Boundary Explorer - Astronomical Results

Astronomical Results

Initial data revealed a previously unpredicted "very narrow ribbon that is two to three times brighter than anything else in the sky". Initial interpretations suggest that "the interstellar environment has far more influence on structuring the heliosphere than anyone previously believed". "No one knows what is creating the ENA (energetic neutral atoms) ribbon, but everyone agrees that it means the textbook picture of the heliosphere—in which the solar system's enveloping pocket filled with the solar wind's charged particles is plowing through the onrushing 'galactic wind' of the interstellar medium in the shape of a comet—is wrong". The Sun is currently traveling through the Local Interstellar Cloud, and the heliosphere's size and shape are key factors in determining its shielding power from cosmic rays. Should IBEX detect changes in the shape of the ribbon, that could show how the heliosphere is interacting with the Local Fluff.It has also observed ENA's from the Earth's magnetosphere.

In October 2010, significant changes were detected in the ribbon after six months, based on the second set of IBEX observations.

"Our discovery of changes over six months in the IBEX ribbon and other neutral atoms propagating in from the edge of our solar system show that the interaction of our Sun and the galaxy is amazingly dynamic" —D. McComas, IBEX principal investigator

It went on to detect neutral atoms from outside the solar system, which were found to differ in composition from the Sun. IBEX discovered the Sun has no bow shock. The speed of the heliosphere in relation to the local cloud is thought to be 52,000 miles per hour, instead of previous estimate of 59,000 mph. Those speeds equate to 25% less pressure on the Sun's heliosphere than previously thought. The velocity of the LISM (Local Interstellar Medium) relative to the Sun's was previously measured to be 26.3 km/s by Ulysses, whereas IBEX measured it at 23.2 km/s.